United States Department oj Agriculture o.

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1 I SYMPOSIUM ON FORAGE UTILIZATION: NUTRITIVE VALUE OF FORAGE AS AFFECTED BY PHYSICAL FORM. PART I. GENERAL PRINCIPLES INVOLVED WITH RUMI- NANTS AND EFFECT OF FEEDING PELLETED OR WAFERED FORAGE TO DAIRY CATTLE 1 N recent years, considerable interest has developed concerning the effects of grinding, pelleting, and wafering on the value of forage. Although the possibility of important management advantages is recognized by the author, this report is concerned only with the evaluation of these various forms as they affect nutritive value. There are differing opinions and the data are incomplete, but there is sufficient information to sketch in the broad picture concerning the effect of physical form of forage on its nutritive value. It will be the purpose of this presentation to first sketch in the broad principles and guidelines necessary to develop an understanding of the effect of feeding ground or pelleted forage to ruminants. Pelleting of concentrates or a mixture of concentrates with forage as a portion of the pellet will not be discussed except as necessary to establish the guidelines and principles. This will be followed by a presentation of data related to feeding ground or pelleted forage as well as wafers to dairy cattle. In the presentation of available information the author has drawn on previous reviews of the subject by Loosli ( 1959), Tillman ( 1961 ), Minson (1963), and Putnam and Davis (1963). Distinction Between Pellets and Wa]ers. Usually wafers, according to present concept, consist of highly compressed forage made from long or coarsely chopped material. The wafers may be round, 2-3 in. in diameter, or square and usually 1-4 in. in length. A specially developed wafering machine is used to compress the forage. The wafers have a bulk density of about 30 lb. per cubic foot (Butler and McColly, 1959; Bruhn, 1957). L. A. MOORE United States Department oj Agriculture o. 1 Presented at a Joint Session of the Animal Science, Dairy and Agronomy Sections at the Annual Meeting of the Association of Southern Agricultural Workers, Jacksonville, Florida, February 5, Dairy Cattle Research Brain:h, AHRD, ARS, ARC, Beltsville, Maryland. 230 Pellets, on the other hand, usually consist of finely ground forage compressed into a pellet ~ to 3~ in. in diameter and ~ to 1~ in. in length. Pellets can be made from forage or concentrates or a combination of the two. The bulk density of pellets is about lb. per cubic foot (Dobie, 1959). Variable Factors Affecting Nutritive Value of Physical Forms o] Forage. Many different factors may affect the nutritive value of ground or pelleted forage. Such factors as the physiological state of the animal, the fineness of grinding, the moisture content of the forage, the heat developed during pelleting, the hardness of the pellet, the original composition, especially the amount of readily available carbohydrate in the forage, the quality of the forage, and the amount of concentrate added to the pellet are all important factors that affect the nutritive value of pellets. The Rumen. In order to understand the effects of the physical form of forage on its nutritive value for ruminants, it is necessary to understand the anatomy, physiology, and bacteriology of the rumen. Such information is available from many sources, a few of which are listed: Benzie and Phillipson (1957), Annison and Lewis (1959), Balch and Campling (1962), Lewis (1961), and Barnett and Reid (1961). Grinding or pelleting forage will be discussed insofar as possible in light of the effects which take place in the rumen. Effects of Grinding or Pelleting Forage on Ruminants Prehension and Rumination. Meyer et al. (1959a), reported pairfed sheep required 20 min. for consumption of pelleted forage as compared to 90 min. for consumption of the same forage chopped. Kick et al. (1937) found that steers required for the prehension of equal amounts of whole hay, 2 in. cut, in. cut, and ground hay, 153, 130, 90, and 78

2 PEI,LETED OR WAFERED FORAGE TO CATTLE 231 rain., respectively. Rumination time was 402, 437, 414, and 277 rain., respectively. Thus, the prehension and rumination time was reduced by fine grinding and/or pelleting. Saliva Secretion. There are no direct data available on the extent of saliva secretion as affected by feeding pelleted forage or on the effect of ration on the 24-hr. production of saliva in ruminants. However, Balch (1958) has shown a three-fold increase in saliva secretion during mastication and deglutition of the same weight of hay as compared to concentrates. It is generally assumed that the feeding of long hay stimulates more secretion of saliva than pellets and some evidence of this is supported by ph observations in the rumen (Cullison, 1961). ph of Rumen Contents. Hinders et al. (1961) noted that tureen ph was reduced from 6.9 to 6.0 when dairy cows were fed dehydrated alfalfa (Medicago sativa) pellets as compared to alfalfa hay as the only feed. Balch and Rowland (1957) noted a decrease in rumen ph when ground and pelleted forage was fed. The ph was inversely proportional to the concentration of VFA. Cullison (1961), as shown in table 1, using rations containing 30% Coastal Bermudagrass (Cynodon dactylon (L) Pets.) hay in the physical form of long, ground, and pelleted feed found the ph of the rumen contents was lower in the animals receiving the pelleted ration (5.22) than the ration containing long hay (6.28). The feeding of a small amount of straw to the animals receiving the pellted ration brought about an increase in ph from 5.22 to This change, the author felt, was due to stimulation of rumination and salivation. Rate of Fermentation in the Rumen. Meyer et al. (1959a) using the lignin ratio technique with pair-fed wethers slaughtered at varying intervals after feeding, found a more rapid disappearance of dry matter, largely holocellulose, at 1~ and 4 hr. after feeding pelleted forage in comparison with coarsely chopped forage. In vitro studies with the rumen ingesta also showed an increased rate of fatty acid and CO2 production for samples taken 1 ~ and 4 hr. after feeding for the pellet-fed animals. Leffel (1960) postulates a more rapid rate of fermentation since he found a higher concentration of VFA as well as a higher proportion of propionic acid in the rumen of pregnant ewes fed ground pelleted alfalfa compared to long hay. Concentration and Proportion o] Volatile Fatty Acids (VFA). Meyer et al. (1959a), using in vitro techniques with rumen ingesta, Leffel (1960) and Van Soest (1955), using in vivo techniques, have reported increased concentration of VFA, while Leffel (1960), Moody (1962) and Van Soest (1955) have noted an increased proportion of propioni'c acid to acetic acid in the rumen of animals at 1~ to 4 hr. after feeding either ground or pelleted forage compared to either chopped or long forage. In one report when intake of pellets was reduced, (Leffel and Komarek, 1961) the concentration of VFA and proportion of propionic acid was the same as when long hay was fed. Balch (1960), as shown in table 2, has summarized some pertinent data in the literature on the effect of ration on the proportions of VFA in rumen contents. Putnam and Davis (1963) found a higher concentration of VFA and of propionic acid in the rumen ingesta in animals fed forage pelleted and reground than in animals fed the same forage in the ground form. Addition of concentrates further increase the differences. Rate o] Passage. Rodrigue and Allen (1960) using stained feed compared the rate of passage of long hay with the same hay ground to TABLE 1. EFFECT OF PHYSICAL FORM OF THE RATION ON RUMEN ph Group I II tii IV V Ground Pelleted + + Tests of Treatment Control Ground Pelleted straw straw significance" On samples pumped from tureen of live animal (I) (III) b On samples obtained from rumen at slaughter (I, II, III, IV, V) By direct readings using special electrode in live animal (I, V) (III) a The means for any two treatment groups not enclosed by the same parentheses are significantly (P<.05) different. b Number of observations in II and V too limited far statistical analysis, cunison (1961).

3 232 MOORE TABLE 2. SOME EXAMPLES OF THE MIXTURES OF VOLATILE FATTY ACIDS (AS MOLAR % OF TOTAL ACIDS) FOUND IN THE RUMEN WITH DIF- FERENT DIETS ~ Species Diet Acetic Prop. Butyric Cow 70 lb. arable silage lb. hay lb. hay lb. ground hay Grazing old pasture, cow B Grazing old pasture, cow A lb. hay, 20 lb. concentrates 16 lb. hay, 16 lb. concentrates, cow C 16 lb. hay, t6 lb. concentrates, cow n 16 lb. ground hay, 4 lb. glucose lb. hay, 18 lb. heated corn 18 lb. ground hay, 18 lb concentrates, cow n 18 lb. ground hay, 18 lb concentrates, cow C 6 lb. ground hay, 18 lb. heated corn lb. hay, 24 lb. concentrates Flaked corn, minerals Sheep Grazing lush pasture Grazing, through year a Baleh (1960). different degrees of fineness. The results, as shown in table 3, quite definitely establish the fact that the ground hay passed through the reticulo-rumen more quickly than long hay and that the finer the grind the more rapid the rate of passage and the greater the depression in digestibility of dry matter. Other workers, Meyer et al. (1959a), Blaxter et al. (1956b), and King et al. (1962) are in general agreement with this concept on rate of passage. Digestibility. Since Minson (1963), Reynolds and Lindahl (1960), and Beardsley (1963), have reviewed in some detail the effect of grinding or grinding and pelleting of forage on its digestibility, only limited data will be presented here and a limited number of references will be cited to bring out the primary points of general interest. Blaxter and Graham (1956a), as shown in table 4, have reported data on the effects of pelleting, fineness of grinding, and level of intake on the digestibility of the various feed constituents. Minson (1963) comments that very fine grinding increases cellulose digestibility in vitro but decreases it in vivo. While there are some exceptions, the weight of data indicate that grinding and pelleting forage depresses dry matter digestibility, particularly the crude fiber fraction. It seems likely that degree of fineness of grinding may be the variable primarily responsible for the differences noted in the literature (Rodrigue and Allen, 1960; Blaxter and Graham, 1956a). Acceptability. Since Minson (1963) has discussed acceptability of ground or pelleted forage in some detail, and since intake will be discussed with each class of animals, it will suffice at this point to record the present concept without further documentation. It is generally conceded that pelleted forage is consumed in larger amounts than the same forage in a long or coarsely chopped form. Generally, the poorer the quality of the forage the greater the difference, and conversely, the better the quality the less the difference in acceptability. The argument for this concept is further strengthened by the fact that when concentrates are fed along with the forage so that a rapid rate of gain results, pelleting the ration has little effect on acceptability. Minson (1963), in summarizing the data on sheep, developed a graph of these relationships as shown in figure 1. The data show that as gain approaches a maximum indicating a TABLE 3. COMPARATIVE RATE OF PASSAGE, IN HOURS, OF HAY RESIDUES BY COWS FED LONG HAY AND THE SAME HAY GROUND TO DIFFERENT DEGREES OF FINENESS ~ Change Item Long hay diet (a) Ground hay diet (b) (a)-(b) Coarse grind 5% b 80-5" 5% b 80-5 ' 5% b " Mean (8 cows) * 8* S.D ~6 ~2.... Med. fine grind Mean (8 cows) * 13" S.D. ~ ~8.... Very fine grind Mean (4 cows) ** 30.2** S.D. ~ ~ a Adapted from Rodrigue and Allen (1960). 5v/v b Indicative of time taken for hay ingesta to pass through abomasmn and intestine. 80-5% e Indicative of time hay ingesta remains in the reticulo-rumen. * Significant (P~.05). ~* Significant (P<.01).

4 Item PELLETED OR WAFERED FORAGE TO CATTLE 233 TABLE 4. MEAN DIGESTIBILITY OF THE CONSTITUENTS OF GRASS PREPARED IN DIFFERENT WAYS ~ 600 gm./day 1500 gm./day Medium Finely Medium ground ground ground Chopped andpelleted andpelleted Chopped and pelleted Finely ground and pelleted Dy matter Crude fiber N.F.E Crude protein Cellulose a Adapted from Blaxter and Graham (1956a). high-quality ration, there is little advantage to pelleting in terms of consumption or gain and vice versa. Meyer et al. (1959b) demonstrated that the effects due to pelleting were primarily due to the grinding of the forage preparatory to pelleting. "When ground alfalfa was moistened with water to control dustiness, feed consumption and gains were increased to almost the same extent as when pelleted forage was fed. The authors suggest that the pelleting process serves to put a fine dusty feed into a more palatable form. Tillman (1961) also points out that the fine grinding is primarily responsible for the favorable effects of feeding pelleted forage. Net Energy Values. A few net energy values have been determined comparing long and pelleted forage. As shown in table 5, Blaxter and Graham (1956a) have reported data on the digestible energy, metabolizable energy and net energy 2.0 ;.5 ~-~ lo ~o z u ~ ~ o5 r-_ [ [ I 1%'a I o.i o.2 0,3 I) LIVEWEIGHT GAIN ON UNPELLETED RATION (lb./day) Figure 1. The effect of pelleting rations of different quality as indicated by rate of gain on the size o~ the increase in consumption by sheep. Adapted from Minson (1963).,% for forage fed at two levels 'with different degrees of fineness of grinding. These are further data from the same experiment as shown in table 4. Meyer et al. (1959a) and Forbes et al. (1925) found no difference in the net energy value of chopped compared to ground or pelleted alfalfa. Discussion of Grinding and Pelleting Effects Most significantly, it should be clear that, while other factors are also involved, the degree of fineness of grinding, with the resulting exposure of forage constituents to fermentation, materially affects the degree of difference observed between long or chopped forage compared to ground or pelleted forage. Compared to normal feeding practices when long or chopped hay is fed, the feeding of ground or pelleted forage results in more rapid prehension with less mastication. This results in less salivation with less secretion of buffer salts into the tureen. Since the feed particles are fine, there is less rumination and probably less stimulation of saliva secretion. Within the reticulo-rumen, because the feed particles are finely divided and easily wetted with more rapid solution of feed nutrients, more rapid bacterial fermentation results with a rapid production of organic acids. There is TABLE 5. CALCULATED ENERGY VALUES. CAL./100 CAL. GROSS ENERGY ~ Method of preparation of the grass Medium Finely ground ground Kind of & & Item energy Chopped pelleted pelleted Digestible Low (600 gm./day) Metabolizable Net Digestible High (1500 gm./day) Metabolizable Net a Adapted from Blaxter and Graham (1956a).

5 234 MOORE an increased concentration of VFA and a consequent lowering of ph further intensified because of a lesser amount of buffer salts from saliva being present. The full consequences of this situation are not completely understood but it is known that the Eh is sometimes raised in rumen contents when ph is lowered, Broberg ( 1957), and Eh, ph, and bacterial growth rate can have profound effects on fermentation products produced by pure cultures of bacteria, Rosenberger and Elsden (1960). Higher propionate and lower methane production suggest that reduction of pyruvate to propionate by available hydrogen is enhanced as compared to reducti6n of carbon dioxide to methan. ph and Eh could well be involved in such reactions. The lowered ph may also increase the rate of absorption of organic acids from the rumen. It is interesting as suggested by Cullison (1961) that the feeding of a small amount of straw stimulated ruminant saliva secretion which in turn resulted in less lowering in ph of the rumen contents by virtue of its buffering effect. Because the ground and pelleted forage is finer in particle size than long or chopped hay, this also results in an increased rate of passage from the reticulo-rumen which in turn lowers the amount of digestion which can take place in the rumen as well as the total digestibility of the dry matter, particularly the cellulosic or crude fiber fractions. Because of the increased rate of passage of ground and pelleted forage from the rumen, more space becomes available for more feed which in turn results in greater consumption of feed dry matter. While it has been suggested (Campling et al., 1961) that the "fill" in the rumen for coarse forage may be relatively constant, 24 hr. after feeding King et al. (1962) have shown that the "fill" for ground and pelleted Bermudagrass hay was less than for long hay. These two factors, amount of "fill" and the rate of passage from the rumen, probably operate together in making more room available in the rumen for more feed. Despite the fact that there is a lowered digestibility with lowered TDN, DE, and ME values for the pelleted forage compared to the same forage in the long form, the NE values are the same when fed on an equal intake basis. Blaxter and Graham (1956a) noted that this effect can be explained by the fact that there is less heat increment because of lowered methane production in the rumen by 9 bacterial fermentation which is closely as- sociated with a lowered proportional production of acetic acid and a higher proportional production of propionic acid. Armstrong and Blaxter (1957) have shown that acetic acid has a higher heat increment than propionic acid. These arguments are further strengthened by the fact that as the quality of long or chopped forage is increased, or as the quality of the total ration is increased by the addition of concentrates to the forage ration, it results in production of a greater proportion of propionic acid and the difference between the long and the pelleted forage ration in terms of gain become less. In fact the differences may entirely disappear. There is also evidence (Beardsley, 1963) that there is an optimum proportion of forage to concentrates for maximum gain which in turn is probably related to optimum ratios of organic acids produced in the rumen. If a high proportion of concentrates are fed in the pelleted feed, feed intake and gain is reduced but efficiency of feed utilization is increased. This observation could be related to a large reduction of the acetate propionate ratio and also to a larger production of other acids such as lactic acid. It is also conceivable that if the quality of the forage is so poor that some nutritive deficiency exists, protein for instance, it would be unlikely that grinding or pelleting would increase consumption. It would thus appear that there are certain limiting conditions under which pelleting may be advantageous. Miller (1961) summarized eight experiments in which feed intake was the same for both non-pelleted and pelleted rations and in which the forage in the rations ranged from 50 to 80%. In these experiments, the pelleted rations produced an increase in daily gain of 9% with 10% less feed per cwt. gain. Leffel (i960) suggests pelleted forage is more valuable per unit weight than long hay for pregnant ewes. This would suggest, contrary to previously cited data, that the pelleted ration had a higher net energy value per unit weight in these experiments. In this connection the possible effects of heating and/or pressure in the presence of some moisture in the forage or steaming during the grinding or pelleting cannot be entirely dismissed as a variable factor affecting the productive value of pellets or even wafers, especially in view of reports of the effects of feeding corn steamed in the process of flaking (Shaw et al., 1960). This might be especially true when the pelleted

6 PELLETED OR WAFERED FORAGE TO CATTLE 235 feed contains some concentrate. Further evidence that pelleting per se may at times increase the efficiency of feed utilization per unit weight compared to long hay is found in data reported by Putnam and Davis (1963). While the data in the literature indicate that fine grinding and pelleting will increase the concentration of VFA in the rumen ingesta due to more rapid fermentation, the evidence also shows that there is a more rapid rate of passage and a smaller amount of rumen ingesta. These offsetting effects raise the question of whether the total amount of VFA absorbed from the rumen in 24 hr. is actually increased as has been surmised. Data in relation to this point are lacking. It appears obvious from the preceding discussion that pelleted forage under certain conditions, when fed to ruminants, results in an increased intake of forage dry matter with an obvious increase in rate of growth, fattening, and milk production. As with any feeding program, it is inevitable that if voluntary feed intake can be increased, the overall efficiency of utilization of the ration for productive purposes is increased because the cost of maintenance is spread over a greater number of units of feed consumed. Feeding Pelleted and Wafered Forage to Dairy Animals Pelleted Forage. In two experiments with lactating cows, the feeding of ground or pelleted forage as the only feed compared to long or chopped forage resulted in increased dry matter intake and increased milk production, Ronning et al. (1959) and Keith et al. (1961), as shown in table 6. It will be noted from the table that there was an apparent decrease in milk fat percentage, digestibility of the crude fiber and in hours to peak of of Cr20~ excretion when the pelleted forage was fed. In other experiments where concentrates were fed in comparisons between pelleted and TABLE 6. EFFECT OF PHYSICAL FORM OF ALFALFA-ORCHARDGRASS HAY ON MILK PRODUCTION ~ Jtem Ground Pelleted Chopped Long Intake of forage, lb./day Milk 4% FCM, lb./day Fat, % )i~estibility of crude fiber, % Rate of passage of C r,.,o,~, hr aadapted from Keith el al. (1961). non-pelleted forage, no difference in milk production has been noted, Ronning et al. (1959), Fossland and Fitch (1958), Jones et al. (1958), and Moody (1962), except Brooks et al. (1962). The latter fed a low level of concentrates plus 2 lb. of long hay to the pellet fed group. In one report, Porter et al. (1953) found that milk production and intake of dry matter was decreased because of the hardness of the pellets. In a preliminary report by Balch et al. (1961) the data do not indicate a difference in milk production when long hay-flaked maize, ground hay-flaked maize, long haymaize meal, and ground hay-flaked maize were compared at equal intake (forage to concentrate ratio 60:40). The feeding of the ground hay rations resulted in a lowered fat test. Minson (1963), Van Soest and Allen (1959), Putnam and Davis (1961) and Rook (1961) have recently discussed the various factors affecting the fat percent of milk. It is generally agreed, though there are exceptions, that feeding limited forage accompanied by heavy feeding of concentrates, grinding, or pelleting of forage lowers the fat test of milk through alteration of the proportions of VFA in the rumen. While the data are not extensive, they indicate that the feeding of pellets acl libitum as the only feed can result in increased feed consumption and milk production and a decrease in fat percent, the latter probably affected by fineness of grinding and readily available carbohydrate. The feeding of concentrates along with ground or ground and pelleted forage caused the difference in level of milk production to disappear with one exception, Brooks et al. (1962). Data on the effects of feeding pelleted forage to growing dairy calves is limited, but it is rather conclusive as reviewed when taken along with the results of feeding beef calves and steers. In two reports, Gardner and Akers (1958) and Hemken et al. (1961) showed that pelleting of forage increased the intake of forage and rates of gain. The data, as reported by Gardner and Akers (1958), are shown in table 7. The results reported by Hemken et al. (1961) showed a greater difference between long and pelleted late-cut alfalfa than for early-cut hay. Miller (1962), working with dairy calves from birth to 8 weeks of age, reported the pelleting of good quality Bermudagrass hay caused an increase in consumption compared

7 236 MOORE TABLE 7. FEED CONSUMPTION AND WEIGHT GAINS OF DAIRY CALVES FROM BIRTH TO FOUR MONTHS OF AGE ~ Ground and Item Long Chopped Ground pelleted No. of calves Hay (all. 3rd cut), lb. Calf starter, lb Milk, lb Daily galn, lb Adapted from Gardner and Akers (1958). to coarsely ground hay. Because the calves fed the coarsely ground hay could compensate for the lowered hay consumption by consuming more starter, there was no difference in rate of growth. In a preliminary report by Balch et al. (1961) a study of the reported data does not indicate any difference in the growth of dairy heifers when long hay flaked maize and ground hay flaked maize, long hay maize meal and ground hay maize meal were compared (forage to concentrate ratio 60:40). Wa]ered Forage. Experimental results on feeding wafers to lactating dairy cows are conflicting probably due to differences in forages, animals used, and wafering procedures. Ronning and Dobie (1962) reported increased consumption and milk production on a wafered alfalfa ration as shown in table 8. While the wafers and long hay were not obtained from one lot of baled hay, they were field wafered and field baled from the same field, cut at the same time. The values for the chemical composition of the forages were similar as shown in table 8. On the other hand, reports from Jones et al. (1958) and Bringe et al. (1958) do not indicate any advantage in terms of lactation from the feeding of wafered forage. Veltman et al. (1962) using dairy cows and heifers, Meyer et al. (1959b) using growing sheep and Wallace et al. (1961) using weaned Hereford calves reported that the feeding of wafers did not increase consumption of forage dry matter. It appears that further data will be required to determine the effect of wafering. The reports do not indicate that wafering forage affects the percentage of fat in the milk to any extent. Side Effects. Besides the effect of lowered fat test on milk from feeding finely ground and pelleted forage, several other effects have been noted. It has been reported by Ward (1961) that the butter oil from the milk of cows fed pellets containing alfalfa forage and sorghum grain, 2:1, was practically colorless and difficult to churn. Hansen et al. (1954) reported that the feeding of pelleted compared to chopped alfalfa resulted in a lowered vitamin A and carotene concentration of the milk fat of dairy cows. When dairy cows were fed pellets and hay ad lib, according to a report by Ward (1961) they consumed 67% pelleted and 33% long hay. When the temperature dropped from 49 to 34 ~ F. the ad lib proportions changed to 60% hay and 40% pellets. Hinders et al. (1961) noted an increase in the consumption of bone meal and salt when pellets were fed to dairy cattle. A discussion of the problems of parakeratosis is presented by Beardsley (1963). It is suggested that the lowered fat test, apparent decrease in carotene and vitamin A in milk fat, parakeratosis, and other effects as a result of feeding pellets are probably related to the ph and Eh in the rumen and altered production of organic acids. The lowered fat test in milk as produced by feeding cod liver oil may also be related to these same effects. There is a strong suggestion in the literature that the feeding of a small proportion of long hay with a pelleted ration may be beneficial, Cullison (1961), and Brooks et al. (1962), and might overcome some of the side effects. Summary Effects of Pelleting Compared to Chopped or Long Forage 1. Time of prehension and mastication reduced. 2. Saliva secretion probably reduced. 3. Decrease in rumination. 4. Increase in rate of fermentation in the rumen. 5. Increase in concentration of rumen VFA one to four hours after feeding. 6. Decrease in ratio of acetate to propionate in the rumen. 7. Decrease in ph in the rumen. TABLE 8. EFFECT OF WAFERING ON CON- SUMPTION AND MILK PRODUCTION" 1% inch s~ inch Item Ba]ed wafer wafer Crude protein of forage, % Crude fiber of forage, % Hay consumed 90% dry matter basis, lb Milk 4% FCM, lb Milk fat, % Solids-not-fat, % a Adapted from Ronning and Dobie (1962).

8 PELLETED OR WAFERED FORAGE TO CATTLE Increased rate of digestion in the rumen. 9. Increased rate of passage of feed particles from the rumen. 10. Decrease in dry matter and crude fiber digestibility usually but not always observed. 11. No difference in net energy values at equalized intake. 12. Increased dry matter intake. 13. Grinding of forage responsible for effects of pelleting. 14. Increased acceptability of finely ground and pelleted forage. 15. The finer the grinding the greater the effect of pelleting. 16. Variation of fineness of grinding probably accounts for variable results (digestibility) reported in the literature. 17. The feeding value of poor quality forage is increased more by pelleting than good quality forage. 18. The feeding of some long hay along with a pelleted ration appears to be advantageous. Feeding Pellets and WaJers to Dairy Animals Compared to Chopped or Long Forage Pelleting an all hay ration results in an increased intake of dry matter and increased milk production. Addition of concentrates to the pellets or feeding concentrates with the pelleted forage causes the differences in milk production to disappear. The feeding of ground or pelleted forage results in a decrease in fat percent of the milk probably related to a lower proportion acetate to propionate in the rumen. Feeding pelleted forage to dairy calves increases dry matter intake and rate of growth, There is a lack of agreement in the literature on the effects of feeding wafers. Literature Cited Annison, E. F. and D. Lewis Metabolism in the Rumen. John Wiley and Sons, New York. Armstrong, D. G. and K. L. Blaxter The heat increment of steam-volatile fatty acids in fasting sheep. British J. Nutr. 11:247. Balch, C. C Observations on the act of eating in cattle. British J. Nutr. 12:330. Balch, C. C Rumen digestion and herbage utilization. Proc. 8th Internat. Grassland Congr. p Balch, C. C., W. H. Broster and V. J. Tuck Influence of grinding hay and cooking maize starch on the utilization of mixed diets for growth and lactation. Rep. Nat. Inst. for Res. in Dairying, Reading, 42. Balch, C. C. and R. C. Campling Regulation of voluntary food intake in ruminants. Nutr. Abst. and Rev. 32:669. Balch, D. A. and S. J. Rowland Volatile fatty acids and lactic acids in the rumen of dairy cows receiving a variety of diets. British J. Nutr. 11: 288. Barnett, A. J. G. and R. L. Reid Reactions in the Rumen. Edward Arnold Ltd., London. Beardsley, D. W Symposium on forage utilization: Nutritive value of forage as affected by physical form. Part II. Beef cattle and sheep studies. J. Animal Sci. 23:239. Benzie, David and A. T. Phillipson The Alimentary Tract of the Ruminant. Charles C Thomas, Springfield, Ill. Blaxter, K. L. and N. McC. Graham. 1956a. The effect of the grinding and cubing process on the utilization of the energy of dried grass. J. Agr. Sci. 47: 207. Blaxter, K. L., N. McC. Graham and F. W. Wainman. 1956b. Some observations on the digestibility of food by sheep and related problems. British J. Nutr. 10:69. Bringe, A. N., R. P. Niedermeier, H. J. Larsen and H. Bruhn Comparison of long hay, large size pellets and field baled legume hay for dairy cows. J. Animal Sci. 17:1164 (Abstr.). Broberg, G Measurements of the redox potential in rumen contents. Nord. Vet. Med. 9:918. Brooks, O. L., W. J. Miller, E. R. Beaty and C. M. Clifton Performance of dairy cows fed pelleted and baled Coastal Bermudagrass and alfala hay. J. Dairy Sci. 45:1188. Bruhn, H. D Engineering problems in pelletized feeds. Agr. Eng. 38:522. Butler, J. L. and H. F. McColly F'actors affecting the pelleting of hay. Agr. Eng. 40:442. Campling, R. C., M. Freer and C. C. Balch Factors affecting the voluntary intake of food by cows. 2. British J. 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