ABSTRACTS OF THE THIRD ANNUAL MEETING OF THE FACULTY OF VETERINARY MEDICINE AND ANIMAL SCIENCE UNIVERSITY OF YUCATAN, MEXICO.

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1 ABSTRACTS OF THE THIRD ANNUAL MEETING OF THE FACULTY OF VETERINARY MEDICINE AND ANIMAL SCIENCE UNIVERSITY OF YUCATAN, MEXICO Merida 6, 7 and 8th July, 980 SECTION SECTION 2 SECTION 3 SECTION 4 SECTION 5 SECTION 6 Forage Production Ruminant Nutrition Ruminant Production Milk and Reproduction Pigs and Poultry Biogas

2 278 Trop Anim Prod 980 5:3. ESTABLISHMENT OF LEUCAENA LEUCOCEPHALA WITH COMPANION CROPS : B Pound 2, Amarely Santana, & Guadalupe Ruiz, CEDIPCA, CEAGANA, Apartado 256, Dominican Republic. Leucaena leucocephala shows great promise as a protein forage for livestock in the tropics. However, one disadvantage is its slow establishment. To make use of the land and to reduce erosion and weed build-up during the first ten weeks, a trial was carried out to evaluate the effect on establishment and total yield of planting companion crops between the rows of leucaena. The companion crops used and their yields as forage' are shown in Table. Their effect on yield from the first two harvests of leucaena are shown in Table 2. Table : Forage yield (x ± SEx) of companion crops Companion crop Forage yield (kg DM/ha) Maize 279 ± 292 Canavalia ensiformis a 2790 ± 340 Sweet potato 97 ± 29 Cow pea 589 ± 39 a Regrowth yielded a further 50 and 2880 kg DM/ha in the first and second harvest of leucaena. Table 2: Leucaena forage yields (kg DM/ha) Companion crop Harvest 2 Total None Maize Canavalia Sweet potato Cowpea the support of the FAO/UNDP project DOM/77/002 is acknowledged 2 Technical! Cooperation Officer, ODA Great Britain 2. EFFECT OF NITROGEN AND PHOSPHOROUS FERTILIZATION ON THE PRODUCTION AND PERCENTAGE PROTEIN OF THREE NATIVE GRASSES OF THE GENUS PASPALUM IN THE STATE OF TABASCO; J Perez and F Melendez N: CSAI, Cardenas, Tabasco, Mexico In this study the following native grasses were studied: (Paspalum notatum) and (P. plicatulum) and (P. conjugatum). The first two were grown in acid soils with low content of available phosphorous and clay sandy soil of crum structure. The last named grass was grown in alluvial clay soil of good fertility. Both places had a humid

3 Trop Anim Prod 980 5:3 279 tropical climate. The following levels were studied; 0, 00, 200, 400 kg N/ha. (using urea as the source of nitrogen) and 0, 40, 80, 20 kg of P2O5/ha (as triple superphosphate). The N was supplied in split applications, 40% in three applications between June and November and the rest in four equal parts between December and March. Phosphorous was supplied in one application incorporating it in the soil at the start of the study. Plots of 3 x 5 m were used and the treatments were distributed in a factorial arrangement using a randomised block design with four replications. Cuts were made with a machete between 4-8 weeks depending on the season. The percentage of N in the grass was determined by the Kjeldahl method. No significant effect was obtained from Paspalum notatum with respect to N level with yields of 5.0,.,.8, 4.7 t/ha of DM in two years for 0, 00, 200 and 400 kg/ha respectively. Nor were there differences in response to phosphorous, 5.0, 0.0, 3.5 and.0 t DM/ha being obtained for the levels in the study. The combination of 00 kg of N and 40 kg of P2O5 gave the best result being 6.t DM/ha. Protein content was increased as phosphorous level increased, the values being 7.7, 8.4, 8.8 and 9.9% respectively; hut there was no response to different N treatments. Yield of P. plicatulum did not respond to N or to P at the levels studied. Protein was increased by N (6.0, 8.5, 9.5, 8.5%) and by P (6.0, 9.0, 9.4, 0.7%) Paspalum conjugatum on the other hand responded to N (22.9, 4.9, 42.6, 29.3 t DM/ha and also to P (22.9, 37.3, 27.6, 35,8t DM/ha).Protein content increased with increasing levels of N fertilizer (8.7, 8.8, 8.8, 0.8%) and increasing levels of P (8.7, 8.8, 9.5, 0.%). There was a marked effect of season, with greater yields in the rainy season compared to the season of northerly winds and the dry season. The yields of DM/ha for P. conjugatum were superior to those for the other grasses in the trial, with respect to DM/ha as was the efficiency of utilization of N and P. 3. EFFECT OF TWO LEVELS OF SOIL FERTILITY ON THE PERCENTAGE LEAF FROM VARIOUS TROPICAL GRASSES IN THE HUIMAGUILLO PLAIN OF TABASCO, MEXICO: J Guadalupe Rivera, F Melendez N and J Perez P. CSAT, Cardenas, Tabasco, Mexico In a study of eight months duration the percentage of leaf in 7 tropical grasses was determined under two levels of soil fertility; the two levels being NPK at and in two sites on the Huimaguillo plain in Tabasco State. The design used was a randomised block factorial (2 x 7 x 2) with 3 replications. There was a highly significant response to variety ( P < 0.0) and a significant interaction between site and variety for the four cuts that were made (P < 0.0). Between sites the difference was less in the third cut(p <0.05) than in the fourth cut (P < 0.0) the only interaction between variety and level of fertilization was in the first cut (P < 0.05) alla in the triple interaction (P < 0.0). The percentage of leaf was very variable with the highest percentage being obtained from P notatum throughout the experiment. The upright tillering type of grasses gave higher percentages of leaf in the season of fastest growth, this parameter diminishing as average temperature decreased which was also true when these grasses entered their reproductive phase. The grasses of stoloniferous habit had a lower percentage of leaf; with less variation than the more upright grasses.

4 280 Trop Anim Prod 980 5:3 4. THE EFFECT OF HEIGHT AND FREQUENCY OF CUTTING ON THE YIELD OF AFRICAN STAR GRASS (CYNODON PLECTOSTACHYUS) IN THE CHONTALPA REGION, TABASCO MEXICO; F Melendez and J Perez CSAT, Cardenas, Tabasco CO, Mexico In the Chontalpa region of Tabasco an experiment lasting 240 days was carried out using African Star Grass. This experimental period included the season of Northerly winds (November to February) and the dry season (March to May). The treatments height of cutting (0, 5 and 0 cm) above soil level and the interval of cutting (24, 40 and 60 days) were compared in a 3 x 3 factorial design with randomised blocks and four repetitions. Plots of 9 m 2 were planted and an area of 2 x 2 m within this was harvested. All the plots received a basal dressing of 300 kg of N/ha/year in 6 applications. The production of DM was evaluated per cut as was the total for each season. Significant effects (P < 0.05) of season on yields of DM were obtained. Yields were higher in the dry season (3. t DM/ha) than in the season of northerly winds (.9 t DM/ha), this being attributed to the effect of lower temperatures in the latter season and its effect on the development of the grass. In the season of northerly winds there was a marked effect (P< 0.0) of the height of cutting on yield. In the rainy season the interval between cuts had a significant effect (P < 0.05) on the production of DM. From the results one concludes that in the season of northerly winds it is better to defoliate at ground level ( 0 cm) with longer intervals between cuts (40 or 60 days) and in the dry season the cuts can be at soil level at intervals of 40 days. 5. THE EFFECT OF HEIGHT AND FREQUENCY OF DEFOLIATION ON FORMATION OF BUDS OF LEUCAENA LEUCOCEPHALA IN THE STATE OF TABASCO MEXICO: Jorge Perez P and F Melendez CSAT, Cardenas, Tabasco, Mexico An experiment was carried out in the experimental fields of CSAT, Cardenas, Tabasco in soils of alluvial origin with a medium to high fertility although with problems of drainage. The experiment lasted one year and the seeds were of a local (Campeche) variety. Plots of one year old leucaena were used and the plot size was 2 x 3 m. Three frequencies of defoliation ( 4, 5 and 6 weeks) and 3 heights of cutting (30, 40 and 50 cm above soil level) were used. Five plants were taken at random and the number of buds formed after each cut was counted. The yield of green material per stalks and leaves was measured from its re-birth. A randomised block factorial (3 x 3 ) with 3 replications was used. Yields increased as the interval between defoliations increased and also with cutting height. The highest average production per cut was obtained with a treatment combination of 6 weeks between cuts at 40 cm of height (943 kg/ha). The greatest yield was obtained in the rainy season, the lowest yield in the winter months and intermediate yields in the dry season. Total production of DM was greatest with a cutting interval of 4 weeks a height of 50 cm (4598 kg/ha) and least with a cutting interval of 6 weeks and a height of 30 cm (873 kg/ha). The number of buds formed was similar for each of the 3 intervals (2), with a tendency to be higher with a cutting interval of 6 weeks and a height of 50 cm. The worst combination of treatments was a height of 30 cm at an interval of 6 weeks when the production of buds was 89. The formation of buds followed the reverse tendency to that of yield being lowest during the rainy season, highest in winter and intermediate during the dry season. The greatest formation of buds was with the longest intervals.

5 Trop Anim Prod 980 5: EFFECT OF HARVEST INTERVAL AND PLANTING DISTANCE ON FORAGE YIELD OF DUAL PURPOSE CROPS : Angela Fernandez, B Pound 2 and Luz Meyreles: CEDIPCA, CEAGANA, Apartado 256, Sto Domingo, Dominican Republic Dual purpose crops (grown for their animal forage and human food components) are seen as flexible and versatile crops for the integrated livestock producer, This trial which is still in progress, examines the effects of planting distance and harvest interval on forage yield and subsequent yield of the human foot components (root/tubers/fruit) for three crops (sweet potato, cassava and plantain). It is apparent from the data in Table, that the effect of planting distance is important in the initial harvests of forage from cassava and sweet potato, but thereafter the plants compensate for spacing differences. However, yield differences are maintained between plantain treatments. Table : Effect of planting distances on forage yield (kg DM/ha) Crop Spacing Harvest Cassava Sweet potato Plantain Close Wide Close Wide Close Wide First Second Third Not harvested Support from the International Foundation of Science, Stockholm, Sweden; and the FAO/UNDP Project DOM/77/002 is gratefully acknowledged 2 Technical Cooperation Officer, ODA, Great Britain 7. SOME RESULTS WITH ELEPHANT GRASS (PENNISETUM PURPUREUM) IN THE NORTH CENTRAL REGION OF VENEZUELA; P J Arias; Instituto de Produccion Animal, Facultad de Agronomia, Universidad Central de Venezuela, Maracay This paper gives results obtained during various years of experimentation with elephant grass in the North central region of Venezuela, The yield of forage with high levels of Nitrogen ( kg N/ha/year) has varied from 28 to 95.4 t DM/ha/year. The principal factor which affects the yield is the cutting frequency: 38.9, 7.9 and 86.0 t DM/ha/year, cutting at 7, 0 and 2 weeks with an efficiency of conversion of energy in the visible spectrum of 2.4, 4.00 and 4.8% respectively. With irrigation approximately 40% of the yield corresponds to the dry season. The efficiency of irrigation has improved progressively from 0.63 to 2.0 kg DM/m 3 of water applied. With high yield the efficiency of application of N reaches an annual average value of 60 kg DM/kg N. With high levels of N, the content of crude protein in DM at 7 and 0 weeks of age averaged 9.6 and 6.3% with an estimated digestibility of 72 and 65%. With high levels of N and harvesting at 7 weeks average mean values in sheep were 63.% digestibility of DM and voluntary feed intake of 2.96 kg DM/00 kg liveweight/d and 67.9 g/dm/kg.75.

6 282 Trop Anim Prod 980 5:3 With cattle in various experiments, the intake has varied between 2.43 and 3.44 kgdm/00 kg liveweight/d. Feed conversion showed extreme values between 2.0 and 7. kgdm/kg of liveweight gain. Feed intakes close to 2% of live weight are only sufficient for maintenance and often are accompanied by loss in weight. It is considered that a reasonable estimate of yield is t DM/ha/year; a DM intake of 2.7% of liveweight, a digestibility of DM of 62% and a crude protein content of 8% with 67% digestibility. Nutrient intake and supplementation is discussed for cows of 450 kg liveweight receiving a basal diet of elephant grass. 8. CAPACITY OF FERTILIZED BUFFEL GRASS (CENCHUS CILIARIS MEAT PRODUC TION IN THE HENEQUEN ZONE OF YUCATAN, MEXICO: M Sandoval, INIA, CAEZOHE, Apdo Postal 485, Suc B, Merida, Yucatan The objective of this experiment was to determine the capacity of Buffel grass pastures for beef production, 54 Zebu bulls with an initial weight of 265 kg were distributed at random to a completely randomised design with 2 replications and with treatments of 3, 4 and 5 animals/ha; a control plot with 3 animals/ha received no fertilizer. The corrals were fertilized with a level of Water and mineralised salt were offered ad libitum. Continuous grazing was used and the animals were weighed each 4 days during the 96 day experimental period. After 2 days the treatment with 5 animals/ha was stopped with no difference in gain/animal/day being apparent. The treatments with 3 and 5 animals/ha had higher daily gains than that with 4 animals/ha although the production of beef/ha was the same. Fertilization rate (N-P-K) Treatments (animals/ha) (control) Grazing period, days Initial weight, kg Final weight, kg Weight gain (animal/d) g Total weight gain/animal, kg Beef production/ha, kg THE CHEMICAL COMPOSITION OF GLYCINE WIGHTII ENSILED WITH DIFFERENT LEVELS OF FORMALDEHYDE AND IN THE PRESENCE OR ABSENCE OF DERINDED CANE : R Munoz, Margaret Gill 2 and Amarely Santana, CEDIPCA, CEAGANA, Apto. 256, Santo Domingo, Dominican Republic The use of high protein forages as supplements to diets based on sugar cane has been shown to increase intake and liveweight gain. Owing to the seasonal production of these forages it would be advantageous to find an efficient means of conservation

7 Trop Anim Prod 980 5:3 283 to enable a longer period of supplementation. Thus Glycine wightii was ensiled in laboratory silos, alone or with three different levels of formalin (2.5, 5.0 or 7.5 g/00 g crude protein). These four treatments were repeated with the addition of 0% derinded cane. Formalin has been used with temperate grass and legume silages to reduce the degree of fermentation, while the addition of sugar in the form of derinded cane should increase the initial rate of fermentation and thus improve fermentation quality. The forage was ensiled in plastic containers (5 kg weight of forage) for one month. Chemical composition data are given in the Table. The addition of both formalin and derinded cane appeared to reduce the degree of fermentation with some evidence of interaction. Treatment ph Total VFAs (mmole %) Formaldehyde, g/00 g protein Glycine alone NH 3 (% DM) Glycine + cane The support of the project FAO/UNDP DOM/77/002 is recognised 2 Technical Cooperation Officer, ODA, UK Ruminant Nutrition 0. EFFECT OF FORAGE AND SUPPLEMENT ON FOOD INTAKE, LEVELS OF GLUCOSE AND KETONE BODIES IN THE BLOOD OF SHEEP FED MOLASSES/UREA BASED DIETS: E Aranda; Colegio Superior de Agricultura Tropical, Cardenas, Tabasco, Mexico Twelve Pelibuey sheep of an average weight of 20 kg were randomised to the following four treatments: A) Molasses/urea (2.5%); B) Molasses/urea (2.5%) and cassava meal; C) Molasses/urea (2.5%) and restricted forage; D) Molasses/urea (2.5%), cassava meal and restricted forage. The molasses/urea was offered ad libitum, elephant grass (Pennisetum purpureum) at a level of.5% of body weight and cassava meal at 50 g/animal/d. The forage and supplements were offered in

8 284 Trop Anim Prod 980 5:3 separate feeders and water and minerals were available ad libitum The animals were maintained in individual cement floored pens in an open sided shed. The experiment lasted 60 d; 36 d adaptation, 20 d to take food intake data 2 d for catheterisation and 2d for blood sampling. Blood samples were taken every 2 hr through teflon catheters (# 6) implanted in the jugular vein. The pattern of food consumption was determined each 4 hr during the last 2 d. DM intake, kg/d No supplement Molasses/urea Cassava meal Restricted forage Cassava and forage Probability Total Molasses/urea Penultimate 24 hr Final 24 hr Blood glucose, mg/00 ml Blood ketone bodies, mg/00 ml VOLUNTARY FOOD INTAKE ON SISAL PULP DIETS: A Rodriguez, D G Harrison, E Owen 2 and D Wyllie, INIP, Mococha, Yucatan and Faculty of Veterinary Medicine, University of Yucatan, Mexico Four experiments were carried out with Pelibuey rams ranging in weight from 5 to 27 kg and adapted to sisal pulp diets for several months to test if sodium or calcium hydroxide could neutralise the pulp and increase the voluntary intake of sisal pulp diets and to see whether salt or sodium bicarbonate could increase food intake through increasing rumen outflow. In each of the first three experiments the diet consisted of ad libitum ensiled sisal pulp and in the fourth experiment of fresh sisal pulp. Minerals and either soyabean or sunflower meal were added to give a crude protein content of 2% in the dry matter. In each of the first three experiments, 5 sheep were used, housed individually in cages and in the fourth experiment 0 pens each containing 8 sheep were used. Food intake was measured over 4-5 days after an initial period of 4-7 days. Water was available ad libitum. In the first experiment salt was added to the diet at levels of 0, 0, 20, 30 or 40 g/kg ensiled pulp and in the second experiment sodium bicarbonate was added at the same levels. In the third experiment 92 ml of a solution of 0, 7, 0, 3 or 6% sodium hydroxide were added to each kg of ensiled pulp and in the fourth experiment 0,.5, 3.0, 4.5 and 6.0 g of calcium hydroxide were used. The additives were mixed just before feeding, except for the sodium hydroxide, which was added 24 hr before. The results show that

9 Trop Anim Prod 980 5:3 285 neutralisation of the pulp by the use of either sodium hydroxide or calcium hydroxide had no beneficial effect on food intake, suggesting that the acids present in the pulp were not inhibiting intake. Additional salt or sodium bicarbonate increased water intake, but did not increase food intake in the manner reported in the literature for concentrate diets, There is a suggestion that the use of sodium bicarbonate might be worthy of further investigation. Level of additive, g/kg sisal pulp Experiment (Salt). Intake of fresh diet, g Linear** Water intake, g Experiment 2 (Sodium Bicarbonate) SEx Sig Linear** Intake of fresh diet, g Water intake, g Experiment 3 (Sodium hydroxide) Linear** SEx - Intake of fresh diet, g Linear** Experiment 4 (Calcium hydroxide) SE - Intake of fresh diet,g Linear** Technical cooperation Officer, ODA, London 2 Faculty of Agriculture, University of Reading England 2. THE USE OF SULPHURIC ACID AS A PRESERVATIVE OF ANIMAL FEEDSTUFFS IN THE TROPICS: E Aranda, CSAT, Cardenas, Tabasco Mexico The efficiency of sulphuric acid as a preservative was tested using 480 kg of fresh cattle blood and 540 kg of green plantains, The treatments were as follows with three replications and using the fresh materials as control: a) for blood, sulphuric acid levels of 40, 60, 80, and 00 ml/kg of fresh blood in concentrations of 20 and 50%. b) for plantains 50, 200,250, 300, 500 ml of 20% sulphuric acid/kg fresh plantain and 40, 60, 80, 00 ml of 50% sulphuric acid/kg fresh plantain. The cattle blood was obtained at the moment of killing and the plantains were obtained in bunches and cut with a machete. An average of 20 kg of each material was put in plastic bags (capacity 30 kg) with addition of sulphuric acid according to treatment and the bags were shaken for 5 minutes daily over a period of 40 d.

10 286 Trop Anim Prod 980 5:3 Samples were taken at the beginning and end of the experiment to determine dry matter (DM), crude protein (CP) and protein solubility for blood and DM, CP and crude fibre (CF) and soluble carbohydrate for plantain, Analyses were made according to AOAC methods. ph was determined at the start and,2, 3, 4, 5, 0, 5, 20, 30, and 40 days using a Beckman Zeromatic potentiometer, The results are presented in the Table. Table : Effect of sulphuric acid on preservation of cattle blood Control 50% H 2 SO 4 (ml/kg) ph DM (%) Crude protein (%) NA* Soluble protein (%) * Not Available The material preserved with 20% sulphuric acid had putrefied by the 8th day and hence the results are not given. Table 2: Effect of acid on the preservation of bananas Control 20% H 2 SO 4 (ml/kg) 50% H 2 SO 4 (ml/kg) ph DM (%) Crude protein (%) Crude fibre (%) Soluble carbohydrate (%).0 NA* NA NA NA NA * Not available 3. THE FERMENTATION OF SUGAR CANE JUICE WITH DIFFERENT LEVELS OF FORMALIN AND UREA : Milagros Bobadilla, and Margaret Gill 2 ; CEDIPCA, CEAGANA, Apartado 256, Santo Domingo, Dominican Republic The use of sugar cane juice in animal feeding systems has resulted in high rates of liveweight gain. However, fermentation of the juice is very rapid and it is essential to find economical means of preserving the juice prior to proposing practical feeding systems. Thus, the possibility of using formalin as a preservative was studied in the laboratory. In addition, since it is necessary to add urea to the juice to ensure efficient use of the sugars the effect of urea on the rate of fermentation was also studied, Significant fermentation of the juice started between 6 and 9 hr after extraction, with volatile fatty acid (VFA) concentrations rising to over 50 meq/liter and ph falling to 3.4

11 Trop Anim Prod 980 5:3 287 after 24 h. Some fermentation occurred on all levels of formalin addition reducing ph from 5.2 (fresh juice) to 4.9 with VFA rising to 5 meq/liter. Further fermentation was delayed for 24 hr by addition of 0.0% Formaldehyde. In contrast to a slow initial rise followed by a continuing rise in VFA concentration, ammonia concentration increased slightly for the first 6 hr and was then stable for at least 72 hr. Addition of urea at 0.8% appeared to increase slightly the VFA production but loss as ammonia was minimal The FAO/UNDP PROJECT DOM/77/002 is acknowledged for support of this work 2 Technical Cooperation Officer, ODA, Great Britain 4. RATE OF BREAKDOWN OF SUGAR CANE FIBRE TREATED WITH SODIUM HYDROXIDE AND ITS EFFECT ON RUMEN METABOLISM: A Priego and J M Zuleta, Colegio Superior de Agricultura Tropical, H Cardenas, Tabasco, Mexico Four Brown Swiss bulls of approximately 500 kg live weight with rumen cannulae were used in a 4 x 4 latin square design. Each experimental period lasted 6 days. On day 0 of each period, 6 nylon bags were inserted into the rumen containing 7 g of sugar cane treated with NaOH. One bag was removed each 24 hr to determine rate of disappearance. On day 3 samples of rumen liquid were taken and rumen ph measured 0, 3 and 6 hr after feeding. On day 5, 00 g PEG were infused to measure rumen flow rate. The basal diet was sugar cane stalks treated with NaOH at levels of 0, 2, 4 and 6% of cane DM (corresponding to 0, 3, 6 and 9g/kg of fresh cane). Each animal also received l kg/d of 75:25 mixture of coconut meal: blood meal. Salt, minerals and water were offered ad libitum. The results are shown in the Table. The effect of sodium hydroxide increased fibre degradation in the rumen and increased food intake by up to 8% with an indication of an increase in rumen flow rate. NaOH, g/kg Cane DM SE Probability Rumen ph 0 hr hr hr Rumen function Volumes litres Flow, litres/d /d Turnover rate, Vol/d, Rate of degradation T /2 (h) Intake, Kg/d Fresh cane Total DM Consumption index, kg DM/00 kg

12 288 Trop Anim Prod 980 5:3 5. RUMEN FERMENTATION AND FUNCTION IN STEERS FED MOLASSES/UREA AND FIVE DIFFERENT FORAGES: R Godoy, FMVZ, Universidad de Yucatan, Mexico. Forage is indispensable in molasses/urea diets in order to prevent toxicity. However, there is no strict definition concerning the composition and rumen digestibility of a forage considered to be adequate for such diets. A latin square design was used to relate composition and rumen degradation rate of five forages with rumen function and nutrient flow to duodenum. The forages were Sweet Potato, Cassava, Leucaena, Banana and Sugar Cane. They were given at the rate of.5% (DM) of live weight in a basal ration of molasses/urea. All the animals received 300 g/d of fish meal and 50g/d of salt and minerals. There was a negative relationship (r 2 =.72) between the protein content and the cell wall content of the forages which we studied. Rumen degradation rate expressed as half time was related (r 2 =.7) to the acid detergent fraction of the forage. The different forage sources did not affect DM intake nor the volume or turnover rate of rumen fluid. Ammonia and rumen ph also showed no difference. The flow of DM to the duodenum was related to the half life and the content of lignin of the forage (r 2 =.78 and.62 respectively). The flow of N to the duodenum was significantly greater when Leucaena was the source of forage (2.58 g N/00 g OM consumed). When the supply of forage in molasses/urea diets is very restricted' then it appears that the type of forage has little significance. Under these conditions it is important to select forage with a high content of protein and with a fibrous fraction that is degraded slowly in the rumen. The financial assistance of IFS, Sweden is gratefully acknowledged. 6. STUDIES ON THE RUMEN FERMENTATION PATTERN IN CATTLE RECEIVING DIETS BASED ON CHOPPED WHOLE SUGAR CANE OR SUGAR CANE JUICE Angela Fernandez, Margaret Gill 2 Fausto Done and T R Preston 3 CEDIPCA, CEAGANA, Apartado. 256, Sto Domingo, Dominican Republic The pattern of rumen fermentation was studied in 6 fistulated bulls, 6 of which received a basal diet of sugar cane juice, 6 received chopped, whole sugar cane and 4 received liquid molasses as the basis of the diet. Half of the animals receiving juice and whole sugar cane also had cottonseed meal (000 g/d for juice and 750 g/d for sugar cane). The animals receiving molasses also had access to protein forages of leucaena, glycine, pare grass and sugar cane tops ( animal on each forage). The animals receiving sugar cane juice also had restricted quantities (2% of liveweight fresh basis) of leucaena forage. After a period of adaptation to the experimental diets, samples were taken of rumen fluid at intervals during 24 hr. The principal results are presented in Table. There were important differences in the parameters of rumen fermentation between sugar cane juice and whole sugar cane. ph was lower and the concentration of VFA higher on cane juice than on whole sugar cane. There was a low population of entodinium protozoa on the cane juice and sugar cane; there was a high population of holotrich protozoa in the chopped whole sugar cane but none in the diet of cane juice. The VFA pattern on cane juice was similar to that found normally in cattle receiving molasses.

13 Trop Anim Prod 980 5:3 289 Table : Rumen fermentation pattern (x ± Sex) Whole sugar cane Cane juice Molasses ph 6.45 ± ± ±.03 VFA, m-eq/litre. 78 ± 5 42 ± 23 0 Protozoa, x0-5 /ml Holotrich 0.5 ±.07 None None Entodinia.20 ±.9.55 ±.23 - VFA, % Molar C2 64.* 52.5 ± * C3 24.0* 22.2 ± * C ±.8 2.0* *From Fernandez et al 980 TAP 5:84 The FAO/UNDP Project DOM/77/002 is acknowledged for support of this work 2 Technical Cooperation officer, ODA Great Britain 3 FAO Consultant in DOM/77/ EFFECT OF PROTEIN SUPPLEMENT AND FORAGE SOURCE ON VOLUNT- ARY INTAKE OF SUGAR CANE JUICE : Margaret Gill 2, Fausto Done and T R Preston; CEDIPCA, CEAGANA, Apartado 256, Sto domingo, Dominican Rep. Two trials were carried out to measure the effects of a protein supplement (cottonseed meal) and two sources of forage (sugar cane or pare grass) on the voluntary intake of freshly extracted sugar cane juice supplemented with 0.5% of urea. In the first experiment eight animals were used fitted with rumen and duodenal cannulas, All animals had free access to the auger cane juice/urea solution and in addition received freshly harvested leucaena forage at the rate of 2% of body weight daily, Half of the animals received kg/d of cottonseed meal. After a preliminary period of one week intake was measured over four consecutive weeks. In the second experiment eight bulls were used all had access to the sugar cane juice/urea together with 750 g/d of cottonseed meal. Four bulls received freshly chopped whole sugar cane at the rate of 5 kg/d while the remaining four had freshly chopped pare grass also at 5 kg/d. Animals in both experiments received 60 g/d of minerals. Table : Intake of sugar-cane juice (% liveweight/day) Expt. Cottonseed meal Without supplement SEx Probability Week ± ± ±.3 NS ±.67 NS

14 290 Trop Anim Prod 980 5:3 Table 2: Intake of sugar cane juice (% liveweight/day) Expt.2 Grass Sugar cane SEx Probability ± The results (Table ) show that there were significant differences in voluntary intake of sugar cane juice during the first two weeks of experiment, the animals receiving protein supplement having higher intakes. However, by week four these differences had disappeared. The better results with the protein supplement in the early stages could be ascribed to the direct effects of the by-pass properties of the cottonseed meal while the improvement in intake on the unsupplemented treatment may well reflect adaptation of the rumen microbial population leading to increasing efficiency of microbial protein synthesis.. The results (Table 2) in experiment two indicating significantly higher consumption of sugar cane juice with grass as the forage source rather than sugar cane confirm previous observations on these two forages. Acknowledgement is made to the FAO/UNDP Project DOM/77/002 for the support of this work 2 Technical Cooperation Officer, ODA, Great Britain 3 FAO consultant in DOM/77/ SUGAR CANE JUICE AS ANIMAL FEED, COMPARISONS WITH MOLASSES FOR MILK PRODUCTION IN DUAL PURPOSE CATTLE ; O Vasquez, Margaret Gill and T R Preston3; CEDIPCA, CEAGANA, Apartado 256, Sto Domingo, Dominican Republic Six crossbred cows and their calves (Holstein X Zebu) were used to compare sugar cane juice and molasses as the energy source. The cows were in the second month of lactation and had similar levels of production. Before beginning the trial, the cows had free access to molasses (2.5% urea), restricted amounts of sugar cane (2% of liveweight) and restricted grazing (6 hr/d) on pasture. The treatments consisted of periods of 5-7 d during which the experimental diets were offered as indicated in the Table. The experimental period began on the day 32 when half of the cows were changed from molasses to fresh sugar cane juice (0.8% of urea) with a Brix! value between 6 and 9. The cows were milked once daily allowing the calf to stimulate milk letdown and subsequently to consume the residual milk. The total milk production (the amount at milking, plus that consumed by the calf; weighing before and after suckling) was measured daily. The results are given in Table. Daily production decreased when sugar cane was the only forage and was lower with cane juice than with molasses. When grazing was reintroduced the yield of milk rose rapidly on the juice and molasses with an indication that the rise was more rapid on juice than on molasses. The calves which were suckled by the cows receiving juice grew more rapidly (332 g/d) than those suckled by the cows receiving molasses (7 g/d). Acknowledgement is made to the FAO/UNDP Project DOM/77/002 for the support of this work 2 Technical Cooperation Officer, ODA, Great Britain 3 FAO consultant in DOM/77/002

15 Trop Anim Prod 980 5:3 29 Table : Daily milk yield in crossbred cows given molasses and cane juice and either sugar cane and/or pasture Molasses milk yield. kg/d Molasses Period (d) Pasture/sugar cane Sugar cane Molasses Cane Juice Sugar cane Pasture/sugar cane Pasture Molasses Molasses Pasture Ruminant Production 9. EFFECT OF THE ADDITION OF NITROGEN AND ENERGY TO FRESH SISAL PULP ON THE GROWTH OF PELIBUEY SHEEP IN CONFINEMENT: A Rodriguez, A Castellanos, Guadalupe Bernal and A Shimada: INIP, Mococha, Yucatan and Department of Nutrition and Biochemistry INIP, Palo Alto, Mexico,DF Two experiments were carried out with growing Pelibuey sheep fed a basal diet of fresh sisal pulp. This was supplemented with: A) 2 sources of nitrogen (urea or soyabean meal); b) 2 sources of energy (Sorghum- cane molasses). In each experiment 84 Pelibuey rams were used distributed at random to 4 treatments with 3 replications per treatment and with 7 animals per replication. Each experimental period lasted 40 days, In the first experiment 3.8, 64.2 or 00% of the non protein nitrogen in the diet (urea together with a mixture of branched chain fatty acids) was substituted for protein nitrogen (soyabean meal). In the second experiment, a 2 x 2 factorial arrangement of treatments was used, in which two energy sources (sorghum and molasses) were compared with the effect of additional branched chain fatty acids (iso acids). In the first experiment there was a significant linear increase in daily gain and in dry matter consumption as the proportion of protein nitrogen increased. In the second experiment the use of sorghum significantly improved daily gain (P<.0). There was no effect due to the use of iso acids. None of the treatments significantly altered dry matter consumption.

16 292 Trop Anim Prod 980 5:3 20, RESPONSE OF GROWING PELIBUEY SHEEP TO VARYING LEVELS OF DIETARY ENERGY: R Gomez, and J Hernandez, INIP, Tizimin, Yucatan, Mexico Thirty two Pelibuey rams of average weight 6.4 kg were distributed at random to 4 treatments with energy contents of 2.6, 2.42, 2.67 and 2.92 Mcal ME/kg (on a dry matter basis). The diets were formulated using sorghum grain, dried grass, soyabean meal, urea and molasses. The energy concentration was altered by varying the proportions of sorghum and grass. The diets were iso nitrogenous (5.2% CP in DM) and feed intake and liveweight gain were measured for 70 days. There was a significant linear increase in daily gain as energy increased; Y= x (r=0.76) as well as an increase in dry matter intake and an improvement in feed conversion efficiency. Diet energy, Mcal/kg Daily gain g/d DM consumption, g/d Conversion, feed/gain THE USE OF POULTRY LITTER AS A SOURCE OF ROUGHAGE AND FERMENTABLE NITROGEN IN A DIET BASED ON MOLASSES : Luz Meyreles and T R Preston 2 CEDIPCA, CEAGANA, Apartado 256, Sto Domingo, Dominican Rep. Eight Zebu steers in individual stalls were used to compare two levels of poultry litter and two methods of feeding in a trial lasting 84 d. The design was a factorial arrangement of the treatments (2 x 2) with two replications. The treatments were:.5 or 3.0 kg/d of poultry litter; and giving the poultry litter and molasses in separate troughs or combining the two components by pouring the molasses on top of the poultry litter. The poultry litter was from a broiler operation and the litter was composed of sugar cane bagasse. The dry matter content was 80% and there was 22% of N x 6.25 in the DM. The molasses contained 2.5% urea (w/w). In addition all the animals received kg/d of whole cottonseed. All animals received a mineral mixture. The principal results are presented in Table. Total voluntary intake was reduced when the higher level of poultry litter was given. Intake was also lower when the poultry litter and molasses were given mixed together as compared with being given separately. The best treatment was the level of.5 kg/d of poultry litter given separately from the molasses which supported a liveweight gain of 780 g/d and a food conversion of 7. kgdm/kg gain.

17 Trop Anim Prod 980 5:3 293 Table : Mean values for animal performance according to the principal treatment effects System Poultry litter, kg/d Separate Mixed Prob Prob. Daily gain, g ±90 Intake kg!/d Molasses ±.09 Poultry litter ±.4 Total DM ±.7 Conversion ±7.0 Acknowledgement is made to the FAO/UNDP Project DOM/77/002 for the support of this work 2 FAO consultant in DOM/77/002 SEx 22. EFFECT OF SUPPLEMENTATION WITH MOLASSES/UREA OR BLOOD MEAL ON THE PERFORMANCE OF BULLS GRAZING ALEMAN PASTURE: A Navarro, Colegio Superior de Agricultura Tropical, H. Cardenas, Tabasco, Mexico Fifty four crossbred bulls were allotted to the following three treatments: A) Continuous supplementation; B) Supplementation in the critical period; C) Without supplementation. The animals grazed continuously a total of 5 ha of Aleman grass (Echinochloa polystachya) divided into 6 equal-sized paddocks. The grass was fertilized with 50 kg /ha in three applications. A stocking rate of 2.5 animals/ha was used in the cool/wet season "nortes" (Oct-Feb) and 3.6 animals/ha during the dry season (Fete-June). The continuous supplementation treatment consisted of 3.0 kg of molasses/urea (2.5%)/d during the season of the "nortes" and 300 g/d of blood meal during the dry season. The treatment of supplement during the critical period only was 3.0 kg/d molasses/urea (2.5%) during the season of the "nortes". Water and minerals were offered ad libitum. The experiment lasted 224 days (26 d in the "nortes" and 98 d of dry season). The principal results are given in the Table. Supplementation Liveweight gain (g/d) Continuous Critical periods None Prob. Cool/wet (Oct-Feb) Dry (Feb-June)

18 294 Trop Anim Prod 980 5:3 23. THE EFFECT OF RESTRICTED ACCESS TO LEUCAENA LEUCOCEPHALA ON LIVEWEIGHT GAIN IN ANIMALS GRAZING AFRICAN STAR GRASS (CYNODON PLECTOSTACHYUS. K. Scherm). J. Palomo S, R. Castro G., F. Melendez N. CSAT, Cardenas, Tabasco, Mexico An evaluation of the response to restricted access to Leucaena leucocephala was measured in a 252 day trial at CSAT in Cardenas. The treatments were 0, 2, 4, or 6 h grazing leucaena with the remaining time spent grazing African Star Grass (C. Plectostachyus) There were 4 paddocks (of ha ) of African Star Grass and 3 compact areas of leucaena (9000 m ). These were grazed by 20 weaned calves (Zebu x Holstein and Zebu x Swiss) with an average weight of 5 kg. The stocking rate was 5 head/ha. in a system of continuous grazing. There were no significant treatment differences in daily weight gain, however, there was a tendency to increase liveweight gain as the time of grazing leucaena increased. The calves grazing only Star Grass had a total gain of 74 kg, while those with 4 h on leucaena had a gain of 04 kg/animal over the same period. The production of meat/ha followed the same tendency with the best production (547 kg/ha) from animals grazing leucaena for 4 h/d and only 369 kg/ha on the control, There were no signs of mimosine toxicity and it is suggested that restricted grazing of leucaena eliminates this risk. National Institute of Agriculture Research. 24. SUGAR CANE JUICE AS CANE FEED: COMPARISONS WITH MOLASSES IN THE PRESENCE OR ABSENCE OF PROTEIN SUPPLEMENT: M Sanchez & T R Preston, Facultad de Medicina Veterarinaria y Zootecnia, Universidad de Yucatan, Merida, Mexico Sugar cane juice has important characteristics as an energy containing feed source for animals within the general framework of a better utilization of the sugar cane plant. The experiment reported here was conducted to obtain preliminary information on animal response to diets based on sugar cane juice in comparison with molasses based diets. Sixteen steers with a mean initial live weight of 27 kg were distributed in pairs to 8 pens. The dietary treatments (replicated twice) were: A) sugar cane juice plus urea (0.5%) with a supplement of kg/d sunflower cake; B) sugar cane juice plus urea without supplement; C) molasses/urea (2.5%) with supplement of kg/d Sunflower cake; D) molasses/urea (2.5%) without supplement. Both the sugar cane juice and the molasses were offered on an ad lib basis. Chopped African Star Grass was used as the forage source on all diets (3% of body weight). Minerals were also fed. Feed refusals were measured daily. The animals were weighed et the beginning of the trial and at 5 d intervals. The trial lasted 75 days. Daily liveweight gains were greater on the sugar cane juice than on the molasses diets. This may be due to a greater efficiency of conversion of the dietary sugars into microbial protein. Sunflower meal supplements resulted in an increase in dietary solids intake from juice and a greater liveweight gain on both molasses and juice.

19 Trop Anim Prod 980 5:3 295 No Suppl. Molasses Sunflower meal No Suppl Cane juice Sunflower meal Liveweight gain, kg/d ±.7.00 Intake, kg/d Juice Molasses Total DM ± Conversion ± SEx Prob TCO, ODA, London, UK Lactation & Reproduction 25. ESTROUS SYNCHRONIZATION WITH CHAROLAIS IN A DRY TROPICAL CLIMATE TREATING ONCE OR TWICE WITH PROSTAGLANDIN F2 ; J M Ponce de Leon S de los Santos, R Ruiz and E Gonzalez, INIP, Palo Alto, Mexico D F and "E! Canelo" Ranch, Tamaulipas The degree of estrous synchronization and fertility were evaluated after one or two applications of prostaglandin F2 (PGF2 ). These were given intramuscularly to Charolais cattle in which a corpus luteum was detectable by rectal palpation. 28 cows and 28 heifers were distributed into three equal lots on the basis of liveweight, body condition ant reproductive state. Three treatments were applied: () Application on the first day of the study, of 30 mg PGF2 (Dinoprost-trometamina ); (2) As above, but with a second injection given days after the first; (3) Without hormonal treatment. The dates of the first application in treatment and the second in treatment 2 are taken as day zero for artificial insemination. Pregnancy was detected by rectal palpation. The percentages of heat observed in the first 5 days were 88.9, 78.9 and 3.6% for treatments, 2 and 3, respectively (P <.05) and from 0-2 days were 00, 94.7 and 00%. Fertility from 0-5 days was 44.4, 3.6 and 2% (P <.05) and from 0-2 days was 6., 68.4 and 89.5% (P <.05).

20 296 Trop Anim Prod 980 5:3 26. SURVEY OF CATTLE IN THE STATE OF YUCATAN: J C Segura, Colegio Superior de Agricultura Tropical, Cardenas, Tabasco, Mexico The present study was started in 974 to obtain information on beef cattle in the state of Yucatan and involved a questionnaire sent to 8,4% of farmers. The state was divided into 3 zones (livestock, sisal and agricultural) and these in turn were divided into 3 subdivisions according to ownership: individual, group or co-operatives. From the information collected meat production (97.%) was the principal objective with the majority of farmers fattening calves (75.3%) Milk production represented.6%. One of the principal problems for the farmers was the absence of extensive grassland in 33.9% of the enterprises sampled, this percentage being greater in co-operatives (85%) and individuals (33.6%). The cooperatives reported worse management in their herds in terms of feed supplementation and its control, disease and parasite control, crop production, calving problems etc. The only genetic tendency observed was the move towards Zebu cattle. 50.8, 5.2 and 5.3% of the co-operatives, individuals and groups used their own calves as bulls. The problems observed thus appeared to be limiting livestock production in the State. 27. PRODUCTION OF MILK IN THE TROPICS: ADVANCES IN THE PRODUCTION OF MILK AND BEEF IN DUAL PURPOSE SYSTEMS; F J Alvarez, G Saucedo and A Arriaga, Centro Demostrativo de Produccion Animal C- 4, Banco de Mexico, Tabasco The data presented were collected from a dual purpose herd of Holstein x Zebu cows kept under grazing management in Tabasco, The production and reproduction data refer to the period 977 up to the present. The system is typical of dual purpose herds with the presence of the calf to stimulate milk letdown and to remove the residual milk after milking. There was an increase in milk production from 000 litres milk per lactation in 977 to 800 litres in 980. This improvement was attributed to the culling of non-productive cows, better management and supplementation with sugar cane, molasses and protein during critical periods. The reproduction data show an important improvement which could be attributed to the change in breeding policy. In 976 only artificial insemination was used while in 977 natural service was introduced for cows which returned to service twice or had a period of 50 d without apparent signs of oestrus. 28. MILK PRODUCTION IN THE TROPICS: MILKING WITH AND WITHOUT THE CALF AND WITH AND WITHOUT SUPPLEMENTATION WITH LEUCAENA LEUCOCEPHALA F J Alvarez, J de Leon y A Ayala; Centro Demostrativo de Produccion Animal, Teya, FIRA, Banco de Mexico This trial was carried out with 34 cows all in their first lactation, representing approximately 75% European genes and 25% Zebu (Holstein X Zebu and Brown Swiss X Zebu). The animals began the experiment at the moment of calving. The principal treatments were as follows: with and without the presence of the calf and restricted suckling, with and without supplementation with restricted grazing of leucaena. The design was a factorial arrangement. The cows were fed on the basis of free grazing, principally on Santo Domingo Star grass, under conditions of irrigation

21 Trop Anim Prod 980 5:3 297 and moderate fertilization. They also received 3 kg/d of a protein supplement during the first 3 months which was later reduced to 2 kg/d. Milking was by machine twice daily, the protein supplement being given at the time of milking. During the four months, the cows on the restricted suckling treatment, suckled their calves twice daily, after each milking for a period of 30 minutes. The calves on artificial rearing received 4 litres daily of milk during the first two months, three litres daily in the third month and two litres daily in the fourth month, when they were weaned. The treatment with Leucaena forage consisted in allowing the cows to graze a compact area of Leucaena for four hours daily in the morning, after milking. Data are given for 72 days of lactation. Grazing Milking Leucaena Pasture With calf Without calf No. of cows Milk production (litres/d) By machine Total Liveweight changes (g/d) Cows Calves Preliminary data for 72 days 2 Including 2.57 litres/d taken by the calves 29. MILK PRODUCTION IN THE TROPICS; REARING OF CALVES ON TWO MANAGEMENT SYSTEMS, WITH AND WITHOUT LEUCAENA FORAGE: F J Alvarez, J de Leon and A Ayala; Centro Demostrativo de Produccion Animal, Teya, FIRA, Banco de Mexico, Merida This experiment was carried out with 26 crossbred calves (Holstein X Zebu ant Brown Swiss X-Zebu, approximately 80% European genes) of both sexes and of 3-4 months of age at the beginning of the trial. The calves had been raised by two systems of management: artificial rearing and restricted suckling. These two systems were maintained throughout the experiment. In each system, half of the calves received Leucaena forage, given at the rate of 2-3% of liveweight together with molasses/urea (2.5%) on a free choice basis. They also received 300 g/d of a protein supplement. The second treatment was grazing (8:0D am until 3:00 pm) together with 600 g/d of protein supplement and molasses/ urea (2.5%) ad libitum. In the group of calves reared artificially, some animals (the younger ones) continued receiving milk at a rate of 2-3 litres daily until they reached four months of age, when they were weaned. The calves in the system of restricted suckling were suckled once daily, after the afternoon milking. Data are presented for the first 85 days of the trial.

22 298 Trop Anim Prod 980 5:3 Feeding Leaucaena Pasture Restricted suckling Management Artificial rearing Liveweight gain, g/d ± 62 Intake, kg/d Molasses/urea.56.7 Protein supplement SEx 30. MILK PRODUCTION IN THE TROPICS: PRELIMINARY OBSERVATIONS ON PERFORMANCE OF JERSEY AND THREE QUARTER ZEBU/SWISS: A Libreros, C Bermejo, and F J Alvarez; Centro Demostrativo en Produccion Animal Los Sabidos, Chetumal Q Roo, Mexico. Preliminary information is presented on 52 Zebu-Swiss and 27 Jersey cows which arrived in September 979, The cows were grazing African Star grass pasture. After their arrival severe outbreaks of anaplasmosis and piroplaemosis were observed mainly in the Jersey herd. After first parturition the cows were mechanically milked twice daily without the presence of the calf. After the second milking the calves were allowed to suckle the residual milk. No decrease in yield was observed without the presence of the calves. The cows were milked once daily for the first 30 days subsequently changing to twice daily. Table : Observations on adaptation to ticks in Swiss/Zebu and Jersey heifers Total Affected ana and/or piroplasmosis Swiss/Zebu Jersey Table 2: Observations on milk production in Jersey and Swiss/Zebu cows in restricted suckling systems Death Once daily milking 2 Twice daily milking 2 Jersey Swiss/Zebu Jersey Swiss/Zebu No. of animals Milk yield First 60 days of lactation 2 The same animals in both systems