Effects of Dietary Levels of Forage and Ruminally Undegraded Protein on Early Lactation Milk Yield by Alpine Does and Doelings

Journal of Applied Animal Research ISSN: 0971-2119 (Print) 0974-1844 (Online) Journal homepage: http://www.tandfonline.com/loi/taar20 Effects of Dietary Levels of Forage and Ruminally Undegraded Protein on Early Lactation Milk Yield by Alpine Does and Doelings A. L. Goetsch, R. Puchala, M. Lachica, T. Sahlu & L. J. Dawson To cite this article: A. L. Goetsch, R. Puchala, M. Lachica, T. Sahlu & L. J. Dawson (2000) Effects of Dietary Levels of Forage and Ruminally Undegraded Protein on Early Lactation Milk Yield by Alpine Does and Doelings, Journal of Applied Animal Research, 18:1, 49-60, DOI: 10.1080/09712119.2000.9706323 To link to this article: https://doi.org/10.1080/09712119.2000.9706323 Copyright Taylor and Francis Group, LLC Published online: 11 Nov 2011. Submit your article to this journal Article views: 33 View related articles Citing articles: 5 View citing articles Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalinformation?journalcode=taar20 Download by: [46.3.205.156] Date: 04 December 2017, At: 13:36

J. Appl. Anim. Res. 18 (2000) : 49-60 Effects of Dietary Levels of Forage and Ruminally Undegraded Protein on Early Lactation Milk Yield by Alpine Does and Doelings A.L. Goetsch", R. Puchala, M. Lachica T. Sahlu, L.J. Dawson E (E(lka) de la Garza Institute for Goat Research Langston University, P.O. Box 730, Langston, OK 73050, USA (Received December 11, 1999; accepted May 12, 2000) Abstract Goetsch, A.L., Puchala, R., Lachica, M., Sahlu, T. and Dawson, L.J. 2000. Effects of dietary levels of forage and ruminally undegraded protein on early lactation milk yield by Alpine does and doelings. J. Appl. Anim. Res., 18: 49-60. Thirty-one Alpiiie does aiid 31 doelings (52*1.62 mid 34*0.86 kg initial body weight, respectively) were used to detcriniiie effects of dieta.ry levels of forage aiid ruininally uiidegraded protein (RUP) aiid change in forage level on ea.rly 1acta.tion perforinaiice. Gods begaii a. 2-week covaride period ad 3-9 days after parturitioii, theii were assigned to treatineiits: 80 = 80% fomge diet; 80R = 80 with added RUP; 40 = 40% forage diet; 40R = 40 with RUP a.dded; 40-80 = 80 in weeks 1-3, transition to 40 in weeks 4-5 and 40 iii weeks 6-16; and 8OR-4OR=8OR iii weelzs 1-3, traiisitioii to 40R iii weelzs 4-5 aiid 40R iii weeks 6-16. Diets were 18-19% crude protein (dry matter ba.sis); fos 80R and 40R, equal crude psotein wa.s supplied by blood, fish aiid fedher ineals, substitutiiig for approxiinately two-thirds of soybea,n meal proteiii. Milk yield was greater (Pc0.05) for 40 mid 40R than for 80 mid 80R, and was influenced (PcO.05) by RUPin weeks 1-3aiid 4-5 (weelzs 1-3: 2.51, 2.74, 2.72, 3.33, 2.44and 2.54kg/day; weeks 4-5: 2.52, 2.73, 3.13, 3.59, 2.56a.nd *Phone: 405/466-3836. Fax: 405/166-3138. Email: goetsch8iiiail.luresext.edu J. Appl. Anim. Res. 0971-2119/2000/$5.00 GSP, India 49

50 A.L. Goetsch aiid coworkers 2.62 kg/day; weeks 6-16: 2.18, 2.33, 2.85, 3.11, 2.54 aiid 3.01 kg/day for 80, 8OR, 40, 40R, 80-40 aiid 80R-40R, respectively). Milk protein coiiceiitratioii was greater (PCO.05) for 40 aiid 40R than for 80 aiid 80R (e.g., week 5: 2.81, 2.72, 2.91, 2.86, 2.76 a.nd 2.94% for 80, 80R, 40, 40R, 80-40 aiid 80R-40R, respectively). 111 coiiclusioii, inilk yield iii a 16-week early lactatioii period was greater with 40 us 80% forage, a.lthough RUP impacted inilk yield oiily early in the experiineiit. Chaiigiiig dietary forage level in early 1acta.tioii of da.iry goats did not iiiflueiice subsequelit productioii. Key words: Goat, lactation, forage, protein. Introduction Increased dietary levels of ruminally undegraded protein (RUP) in early lactation has in many instances improved milk yield by dairy cows, depending on factors such as adequacy of ruminally degraded protein, production potential and diet digestibility (NRC, 1989; Bachman, 1992; Polan, 1996). However, in the few studies with goats conducted in this area, added RUP has not enhanced performance (Lu et az., 1990; Sahlu et al., 1993; Brown-Crowder et ul., 2000). Thus, there is need for experimentation to determine what, if any, experimental conditions are conducive to,milk yield responses by dairy goats to added RUP. Physiological processes such as milk synthesis require energy; hence, dietary forage level or digestibility may impact the potential for use in milk synthesis of the increased quantity of absorbed amino acids with added RUP. Parity could be important as well, as influencing potential for milk production and nutrient and energy needs for body weight gain during lactation. Feed intake by dairy goats peaks after the plateau in milk production (AFRC, 1998). Factors limiting the rate at which feed intake increases in early lactation are not well understood. Considerable,changes in gastrointestinal tract and liver metabolism occur at this time, notably marked increases in mass and heat production by the gut associated with elevated protein synthesis (Freetly and Ferrell, 1997). According to current theories of physiological feed intake control focusing on efficiency of energy metabolism (Ketelaars and Tolkamp, 1992a,b; Tolkamp and Ketelaars, 1994; Goetsch, 1998), heat produced by the gut and liver may directly affect feed intake. In accordance, the later peak in feed intake than milk production could relate in part to the time needed

Diets for Alpine goats 51 for increased mass of visceral tissues (Freetly and Ferrell, 1997). That is, substantial heat production associated with increased gastrointestinal tract protein synthesis in early lactation could slow the rise in feed intake. Hence, means to shorten the time during which considerable energy is expended and heat is produced in early lactation to increase mass and metabolic capacity of the gut could shorten the period when ingested feed is insufficient to support milk yield, when maternal stores are used for lactation support, and may increase level and efficiency of milk production by dairy goats. In this regard, the quantity of energy absorbed and digesta residing in and passing through the digestive tract appear to influence visceral tissue mass and energy use (Goetsch, 1998). Therefore, a relatively high dietary level of forage in early lactation to increase the rate at which gut metabolic capacity increases might alter the level or length of peak feed intake or the rate of subsequent decline. Hence, objectives of this experiment were to determine effects of the dietary level of RUP and levels of and changes in dietary forage on Alpine doe and doeling performance in early lactation. Materials and Methods Thirty-one Alpine does and 31 doelings (52h1.62 and 34h0.86 kg, respectively) in low to moderate body condition were used. Goats; began a 2-week covariate period at 3 to 9 days after parturition over a 5-week period, then were randomly assigned to treatments. During the covariate period, all goats were fed a 50% forage, 16% crude protein (CP) diet (dry matter basis). Thereafter, treatments imposed were: 80 = 80% forage diet; 80R = 80 with RUP; 40 = 40% forage diet; 40R = 40 with RUP; 40-80 = 80 in weeks 1-3, gradual transition to 40 in weeks 4-5 and 40 in weeks 6-16; and 80R-40R=80R in weeks 1-3, transition to 40R in weeks 4-5 and 40R in weeks 6-16. For 80R and 40R, equal CP was supplied by blood, fish and feather meals, substituting for approximately two-thirds of soybean nieal CP (Table 1). Based on NRC (1989) and Preston (1998), RUP was approximately 25, 37, 30 and 50% of total CP and ruminally degraded protein was 22, 19, 17 and 13% of total digestible nutrients for 80, 80R, 40 and 40R diets, respectively. Thus, ruminal levels of nitrogenous compounds should have been ample to support microbial protein synthesis as influenced by fermentable organic matter supply.

52 A.L. Goetsch and coworkers Table 1 Ingredient composition of diets fed to Alpine goats in early lactation Item D;.et' 80 80R 40 40R Cottonseed hulls Alfalfa hay Ground corn Soybean meal Blood meal Fish meal Feather meal Molasses Fat Dicalcium phosphate Limestone Ammonium sulfate Sodium bicarbonate Vitamin premix' Trace mineral salt3 Magnesium oxide 20.00 60.00 0.73 10.00 1.46 0.25 0.50 0.76 0.30 20.00 60.00 2.59 3.33 1.40 1.84 1.42 1.31 0.25 0.50 0.76 0.30 20.00 20.00 31.31 17.60 1.08 1.20 0.25 1.00 0.50 0.76 0.30 20.00 20.00 36.09 5.33 2.43 3.18 2.46 0.89 0.81 0.25 1.oo 0.50 0.76 0.30 'XO = 80% forage; 80R = 80% forage and ruminnlly undegraded protein; 40 = 40% forage; 4011 = 40% forage and ruminally undegraded protein. 'Contained 2200 IU vitamin A, 1200 IU vitamin D, and 2.2 IU vitamin Elg. Tontained 9548.5% NaCl and >0.24% Mn, 0.24% Fe, 0.05% Mg, 0.032% Cu, 0.011% Co, 0.007% I and 0.005% Zn. Goats were maintained in confinement with individual feeding in Calan gates (American Calan, Inc., Northwood, NH, USA). Diets were completely mixed and fed once daily at 0900 hour at approximately 110% of consumption on the preceding few days. Goats were milked at 0400 and 1600 hours. Body weight (BW) was determined at the beginning of the covariate period, at the start of the experiment and after 3,5,9, 12 and 16 weeks. Milk samples from both milkings were obtained in weeks 1, 3, 5, 7, 11 and 15, and analysed for fat, protein (N x 6.38) and lactose with an infra-red spectrophotometer (Multispec2; Multispec, Wheldrake, NY, USA). Ort samples were obtained once weekly and diets were sampled at times of batch preparation. Diet and refusal samples were analyzed

Diets for Alpine goats 53 for dry matter (DM), CP (AOAC, 1990) and neutral detergent fiber (filter bag technique; ANKOM Technology Corp., Fairport, NY, USA). Overall, refusal composition was similar to that of diets offered. Data were analyzed by General Linear Models procedures of SAS (1990). Measures in the covariate period significantly (Pc0.05) affected most variables and, thus, were included in models. Models also included dietary treatment and parity. There were no significant interactions between dietary treatment and parity (P>0.05); thus, this term was dropped from models. Because of the nature of the dietary treatments, measures made at different times were analyzed separately. Differences among means were determined by contrasts: 80 us 40% forage; diets without us with added RUP; interaction between levels of forage and RUP; 80-40 us 40; and 80R-40R us 40R. Results Average dietary CP concentration was 19.1, 18.6, 18.2 and 18.9%, and neutral detergent fiber level was 33.2, 33.1, 44.8 and 43.8% (DM basis) for 40, 40R, 80 and 80R, respectively. Dry matter intake was greater (P~0.01) for 40 us 80% forage diets in weeks 1-3 and 4-5, although DM intake was similar (PsO. 15) between forage levels at other times (Table 2). Likewise, DM intake was less (Pc0.05) for 80-40 us 40 and for 80R-40R us 40R in the first 3 weeks of the experiment. Dry matter intake was greater (Pc0.05) for multiparous than for primiparous goats in the first 10 weeks of the experiment. Although, relative to BW, DM intake as a percentage of BW (data not shown) was greater (Pc0.05) for doelings us does. Other than for 80-40 and 80R-40R treatments, within treatment differences in DM intake among weeks 1-3, 4-5 and 6-16 were not substantial compared with changes in DM intake as lactation advances in dairy cows (NRC, 1989). There was slightly greater change in feed intake for 80% forage diets early in the experiment as time advanced compared with 40% forage diets. Body weight change differences between does and doelings varied among the various segments of the experiment, although during the entire experiment doelings gained slightly more BW than did does (i.e., 1.7 kg; P = 0.09). Milk yield was greater (PcO.01) for 40 us 80% forage throughout the experiment (Table 2). Addition of RUP to the diet increased (P=0.03) milk yield in weeks 1-3 and 4-5; however, effects later were

Table 2 Effect of different levels of and changes in dietary forage and ruminally undegraded protein on Alpine doe and doeling dry matter (DM) intake, body weight (BW) change and milk yield in early lactation Diet' Animal I te 111 LVeek SE SE Effect 80 80R 40 40K 8040 80R-40R Doeling Doe '80 = 80% forage; 80R = 80% forage and ruminally undegraded protein; 40 = 40% forage; 40R = 40% forage and ruminally undegraded protein; 80-10 = 80 in weeks 1-3, transition from 80 to 40 in weeks 4-5 and 40 in weeks 6-16; 80R-40R = 80R in weeks 1-3. transition from 80R to 40R in wecks 4-5 and 40R in weeks 6-16. 'Effect: F and f = forage level (P<0.05 and 0.10, respectively); Rand r = ruminally undegraded protein level (Pc0.05 and 0.10, respectively); A-0 = difference between 80-40 and 40 (PX0.05); A-R = difference between 80R-40K and 40R (PcO.05); P and p = parity (Pc0.05 and 0.10, respectively). I>R1 intake (kg/day) IJ\V change (kg) Milk yield (kg/day) 1-3 4-5 6-16 6-9 10-12 13-1G 1-16 1-3 4-5 6-16 6-9 10-12 13-16 1-16 1-3 4-5 6-16 6-9 10-12 13-16 1-16 2.03 2.02 2.19 2.15 2.18 2.18 2.32 2.26 2.19 2.21 2.04 2.08 2.16 2.18 1.68 2.64 0.68 0.82-0.19 0.29-0.27 0.54-1.32-1.53 1.94 1.90 2.71 4.37 2.51 2.74 2.52 2.73 2.18 2.33 2.54 2.71 2.29 2.42 1.72 1.89 2.28 2.46 2.38 2.52 2.44 2.52 2.28 2.38 2.41 2.50 2.33 2.43 2.12 2.23 2.32 2.43 2.27 4.64 0.71 1.13 1.62 2.50 0.96 1.12 0.73 0.96 2.03 2.73 G.71 8.66 2.72 3.33 3.13 3.59 2.85 3.11 3.19 3.48 2.86 3.15 2.50 2.70 2.86 3.21 1.96 2.38 2.20 2.42 2.23 1.94 2.17 1.81 4.27 3.24 1.02 0.12 1.98 9.21 2.44 2.56 2.54 2.96 2.59 2.08 2.52 1.90 2.34 2.43 2.60 2.40 2.28 2.32 2.20 2.12 1.84 0.30 0.04 2.47 7.13 2.54 2.62 3.01 3.29 3.03 2.73 2.88 0.110 0.118 0.106 0.114 0.113 0.107 0.096 0.928 1.192 0.958 0.821 0.673 0.778 1.218 0.141 0.148 0.178 0.166 0.203 0.189 0.153 1.90 2.36 2.0j 2.63 2.16 2.39 2.21 2.62 2.20 2.39 2.07 2.17 2.10 2.42 1.67 3.42 2.20 1.04 2.27 0.82 1.24-0.01 0.38-1.35 1.84 2.51 7.33 5.61 2.43 2.59 3.13 2.64 2.70 2.92 3.14 2.52 2.71 2.29 2.26 259 2.81 0.073 0.083 0.068 0.075 0.075 0.073 0.063 0.655 0.714 0.601 0.482 0.414 0.459 0.698 0.102 0.102 0.129 0.121 0.147 0.144 0.111 F, A-R, P F,P P P FJ' r,p A-0 f, P P f! P F,P F,R,A-R,P F,R,A-0, -4-R.P F F F F F,r

Diets for Alpine goats 55 not significant (P>O. 10). Overall in the 16-week experiment, increased dietary RUP increased (P=O.O9) milk yield. Alternate feeding treatments (i.e., 80-40 and 80R-40R) resulted in milk yield similar to that for corresponding 40% forage treatments in weeks 6-9, 10-12, 13-16 and 6-16. Doelings produced less (P<O.Ol) milk than does in weeks 1-3 and 4-5, but milk yield thereafter was similar (P>O. 10). Use of 40 us 80% dietary forage increased (P<O.Ol) the percentage of protein in milk throughout the experiment (Table 3). Thus, the effect of forage level on milk protein yield was greater than on milk yield and protein concentration. Conversely, dietary RUP level did not alter the percentage of protein in milk; hence, effects of level of RUP in the diet on milk protein yield in weeks 1-3 (P=0.02) and 4-5 (P=O.lO) were functions of changes in milk yield. In contrast to protein, dietary treatments did not alter the concentration of fat in milk (P>O.lO). Findings were fairly similar for the concentration of lactose in milk and lactose yield. Concentration of protein, fat and lactose were similar (PnO. 10) between primiparous and multiparous goats. Forage level Discussion Greater feed intake for diets with 40 us 80% forage in weeks 1-3 can account for all or most of the difference in milk yield, although presumed greater digestibility for 40% forage diets contributed to differences in weeks 4-5 and 6-16 as well. The magnitude of difference in milk yield between 40 and 80% forage appeared greater early in the experiment when intake was significantly greater for 40% forage than later with only numerical differences in feed intake. In accordance, the ratio of milk yie1d:dm intake was 1.21, 1.32, 1.20, 1.34, 1.17 and 1.34 (SE 0.067) in weeks 1-3; 1.09, 1.23, 1.24, 1.47, 1.03 and 1.20 (SE 0.064) in weeks 4-5; and 0.97, 1.05, 1.24, 1.31, 1.10 and 1.26 (SE 0.058) in weeks 6-16 for 80, 80R, 40, 40R, 80-40 and 80R-40R, respectively. Body weight change data suggest that increased nutrient absorption for 40 us 80% forage was slightly greater than that required for milk production, eliciting a greater increase in BW in the 16-week experiment for 40 us 80% forage. This difference resulted from a cumulative effect of mostly numerical differences in segments of the experiment rather than to an appreciable difference in any particular period.

u1 Table 3 Q, Effect of different levels of and changes in dietary forage and ruininally undegraded protein on Alpine doe and doeling milk protein, fat and lactose concentrations and yields in early lactation Diet' Animal Item Week S E SE Effect 80 80R 40 40R 80-40 80R-IOR Doeling Doe Protein Concentration (%) Yield (glclay) Fat Concentration (%) Yield (g/day) Lactose Concentration (%) Yield (g/day) 1.3 2.99 2.99 3.15 3.11 2.98 3.13 5 2.81 2.72 2.91 2.86 2.56 2.91 7,11,15 2.48 2.51 2.86 2.69 2.74 2.68 13 52.1 79.1 91.1 101.3 73.6 78.8 5 70.6 72.8 92.2 104.0 53.7 75.0 7,11,19 54.2 56.6 79.9 83.3 50.5 59.2 13 3.60 3.60 3.80 3.42 3.55 3.81 5 3.66 3.65 3.43 3.12 3.24 3.48 7,11,15 3.21 3.22 3.19 3.15 3.14 3.15 1.3 88.3 94.1 104.3 114.3 82.1 101.9 5 89.3 103.8 105.7 119.1 81.6 99.8 7,11,15 71.2 71.7 85.3 99.2 55.4 96.2 13 4.45 4.38 4.23 1.39 4.32 4.09 5 4.09 4.10 4.24 4.20 4.17 4.08 7,11,1.5 3.81 3.91 3.90 3.91 3.98 3.87 13 108.9 118.7 120.3 145.1 106.8 104.4 5 104.3 112.1 132.7 154.7 111.3 108.8 7,11,15 83.5 90.9 111.3 123.2 101.3 115.6 0.090 3.14 3.02 0.066 2.8i 2.79 0.071 2.iO 2.62 3.49 74.7 90.7 4.29 7G.3 85.2 4.19 52.9 68.4 0.185 3.56 3.50 0.269 3.41 3.42 0.182 3.16 3.20 6.61 84.8 110.2 12.32 83.8 116.0 6.17 75.8 90.5 0.084 4.30 4.32 0.061 4.12 4.17 0.052 3.87 3.92 6.40 102.6 131.1 6.83 108.1 133.2 6.85 101.5 105.1 0.052 F 0.038 f 0.041 I:? 2.51 F,R,.4-0, A-R,P? 3.08 F,A-0,A-R.P Q 3.01 F,a-o s 0 m 3-0.105 p 0.156 9-0.106 R. 4.40 F,A-0,P 8.20 P 4.11 F,P 0.049 0.036 0.031 4.53 F,R,A-R.P 4.83 4.74 F '80 = 80% forage; 80R = 80% forage and ruminally undegraded protein; 40 = 40% forage; 40R = 40% forage and ruminally undegraded protein; 80-40 = 80 in weeks 1-3, transition from 80 to 40 in weeks 4-5 and 40 in weeks 6-16; 80R-40R = 80R in weeks 1-3, transition from 80R to 40R in weeks 4-5 and 40R in weeks 6-16. *Effect: F and f = forage level (Pc0.05 and 0.10, respectively); R = ruminally undegracled protein level (Pc0.05); A-0 and a-o = difference between 80-40 and 40 (Pc0.05 and 0.10, respectively); A-R = difference between 80R-40R and 40R (Pc0.05); P and p = parity (P<O.O5 and 0.10, respectively). 0 0 e 0 % s d

Diets for Alpine goats 57 The most notable dietary treatment effect on milk composition was the greater concentration of protein with 40 us 80% forage. This may have been due to the anticipated greater microbial protein synthesis for 40 us 80% forage, thereby increasing intestinal amino acid absorption and amino acid availability for use in milk synthesis, and to a positive influence on milk protein synthesis of greater ruminal propionate production and absorption expected with 4090 forage (NRC, 1989; Bachman, 1992; Polan, 1996). RUP level The milk production response to added dietary RUP in weeks 1-3 differed from use of 40 us 80% forage, in that RUP did not impact feed intake. Thus, the response to RUP appeared due to increased amino acid absorption rather than to a simultaneous effect on absorbed energy, as was the case for use of 40 us 80% forage. Body weight change data do not indicate that increased dietary RUP increased mobilization of body energy stores to support milk production, as has been noted in lactating dairy cows (0rskov, 1992). There was not substantial mobilization of body tissue energy stores for milk production with any treatment, which reflects the low to moderate body condition of animals at parturition. In this regard, initial BW were considerably less and BW gain was much greater than seen by Lu et al. (1990) and Sahlu et al. (1993) in previous early lactation experiments with the same Alpine herd. As noted previously, the milk yield response to increased RUP occurred in weeks 1-3 and 4-5 of the experiment but not later in weeks 6-16. The effect of RUP level in weeks 6-9, 10-12 and 13-16 was significant at P=O. 18, 0.30 and 0.35, respectively, and analysis of milk yield by week yielded RUP level probabilities of 0.05, ~0.01, 0.04, 0.03 and 0.10 in weeks 1, 2, 3, 4, 5 and 6 of the experiment, respectively, with probabilities greater than 0.15 in subsequent weeks. Thus, responses to added dietary RUP may be most likely and(or) greatest in periods of lactation with greatest production. In accordance, Lu et al. (1990) did not observe significantly greater milk yield by Alpine doelings consuming diets based on meat and bone meal us soybean meal; however, milk production was numerically greater in the first part of the 12-week early lactation experiment but not later. Sahlu et al. (1993) did not affect milk production by Alpine doelings in early lactation by feeding diets with

58 A. L. Goetsch and coworkers heat-treated us regular-soybean meal, although diets were higher in corn grain than the present diets. Conversely, the same rationale does not appear applicable to does us doelings in the present experiment, with greater milk production by does. This might in part be explained by low to moderate body condition of both doelings and does at the start of the experiment, resulting in only a small difference in BW gain between parities and no periods of BW loss with 40% forage diets. In addition, the greater requirement for energy relative to protein for BW gain us milk production (NRC, 1989) probably contributed to effects on BW gain of dietary forage level but not of RUP. The interaction between dietary forage and RUP levels in milk yield was not significant, although numerically the response to RUP early in the experiment was greater with 40 us 80% forage. Perhaps with a greater number of observations, this interaction might have been apparent. Because milk production is a coordinated process, requiring a greater supply of energy for use in milk synthesis of an increased quantity of absorbed amino acids, responses to increased RUP should be most llkely or greatest in magnitude when the supply of absorbed energy is high. Alteiwxte treatiiieicts Results of this experiment do not support the hypothesis stated earlier regarding dietary changes that may advantageously affect levels and patterns of change in feed intake and milk production in early lactation. However, changes with time in feed intake and milk production were not as expected. AFRC (1998) summarized that milk yield generally peaks 6-9 weeks after kidding and feed intake in the third month of lactation, thus with negative energy balance in the first 2 months of lactation. Perhaps greater initial BW and condition, conducive to mobilization of body energy stores, could have increased milk production and influenced responses to such dietary treatments. Early feeding of 80% forage diets for 80-40 and 80R-40R did not markedly affect subsequent performance when consuming 40% forage diets compared with continuous feeding of 40% forage, although milk yield in weeks 6-16 for 80-40 was numerically (P=O. 19) lower than for 40. Therefore, a limited nutritional plane early in

Diets for Alpine goats 59 lactation may not greatly alter milk production by dairy goats later in lactation with feeding of a higher quality diet. In conclusion, milk yield and protein concentration for doelings and does in low to moderate body condition were greater with 40 us 80% forage throughout the 16-week early lactation period, although RUP significantly affected milk production only in the first segment. Over the entire 16-week period, BW gain was greater with 40 us 80% forage, and doelings increased in BW slightly more than did does. Responses to dietary forage and RUP levels were similar between doelings and does, and forage level did not significantly affect responses to dietary level of RUP. Changing dietary forage level in early lactation of dairy goats did not significantly influence subsequent production. References AFRC. 1998. The NzLtrition of Coats. CAB International, New York, NY. AOAC. 1990. Official Methods of Airalysis (15th Edition). Association of Official Analytical Chemists, Washington, DC. Bachman, K.C. 1992. Managing milk composition. In: Van Horn, H.H. and Wilcox, C.J. (Editors), Large Dairy Herd Mairagemeirt. pp 336-346. Management Services, American Dairy Science Association, Champaign, IL. Brown-Crowder, I.E., Hart, S.P., Cameron, M., Sahlu, T. and Goetsch, A.L. 2000. Effects of dietary protein source on performance ofalpine does in early lactation. Small Ruminant Res.. in press. Freetly, H.C. and Ferrell, C.L. 1997. Oxygen consumption by and blood flow across the portal-drained viscera and liver of pregnant ewes. J. Anim. Sci., 75: 1950-1955. Goetsch, A.L. 1998. Splanchnic tissue energy use in ruminants consuming foragebased diets ad libitzm: observations, causes, and consequences. J. Anim. Sci., 76: 2737-2745. Ketelaars, J.J.M.H. and Tolkamp, B.J. 1992a. Towards a new theory of feed intake regulation in ruminants. 1. Causes of differences in voluntary feed intake: critique of current views. Livest. Prod. Sci., 30: 269-296. Iietelaars, J.J.M.H. and Tolkamp, B.J. 1992b. Towards a new theory of feed intake regulation in ruminants. 3. Causes of differences in voluntary feed intake: in search of a physiological background. Livest. Prod. Sci.. 31: 235-258.

60 A.L. Coetsch and coworkers Lu, C.D., Potchoiba, J., Sahlu, T. and Kawas, J.R. 1990. Performance of dairy goats fed soybean meal or meat and bone meal with or without urea during early lactation. J. Dairy Sci., 73: 726-734. Orskov, E.R. 1992. Protein Nutrition iiz Rziiiiinants (2nd Edition). Academic Press, New York, NY. NRC. 1989. Nutrient Requireineizts of Dairy Cattle (6th Revised Edition). National Academy Press, Washington, DC. Polan, C.E. 1996. Evaluation of sources of protein and their contributions to amino acid adequacy in the lactating cow. In: Kornegay, E.T. (Editor), Niltrieizt Martageineitt of Food Aizirnals to Enhance and Protect the Enuironrneizt. pp 135-140. Lewis Publishers, New York, NY. Preston, R.L. 1998. Typical composition of feeds for cattle. Beef, pp FC2-FC15. Sahlu, T., Fernandez, J.M., Jia, Z.H., Akinsoyinu, A.O., Hart, S.P. and Teh, T.H. 1993. Effects of source and amount of protein on milk production in dairy cows. J. Dairy Sci., 76: 2701-2710. SAS, 1990. SAS/STAT User's Guide (Version 6, 4th Edition, Vol. 2). SAS Institute Inc., Cary, NC. Tolkamp, B.J. and Ketelaars, J.J.M.H. 1994. Efficiency of energy utilization in cattle given food ad libitzm: predictions according to the ARC system and practical consequences. Anim. Prod., 59: 43-47. q.m. W?T, m. m, q. m, a. Tmq m.3. mi wm-$=im &*4~ysJmc?*rnJmrfts&Jft-i-f;4;ft m- ik%%tii smrfts& 3.37 6M-t Jr;rsmwRa* (5d) 2-87 &$mtti *W*rn$?JET m b4tvl m m Sm T$l$ f?iy 31 3- (52k1.62 f%?j W$Wj vh (34k0.86 f%t W7f%%?lfk Om) W VTh f?3ll TIT1 RFJ $ 3-9 f@i zfir 2 FdK $ IT6!R+Fl& 7m!Th 54T, v?m 80=80% TJ Om) 2-87 31 %jfl$i% m 807 = 80 3l? $ WT F i d ; 40 = 40% Jmn; 407 = 40 $ Fis-Td; 40-80 = 80% TJ C!'T! 807-407 = 40-80.rft 5 d $ FPT 1-3 FdK qell W?l: UTE 4 4 5 tim 40% dk&m 6-16 UTE?m40% WJKFfh TITI srmffg?j"wd 3 18-19% 3 N N %&i ell, 5W 807 dk 407 J?i ti T#l7 @, rfn @ 2-87 @?I TmT;I mt ti %&i m m TIT dk s;rft 3-Rim$ smrfts 7hFfI=l %&i 7m Fi-wTw m mrl 8!W@Ri 80 dk 807 $I & 40 3.37 407 d W?JET 3FTFFI?Th:&FF $I gell S d ql Tf 40 9 407 sell 80 4 807 &?Jq %&i$ mt3f$% $1 $77 Vk'Jl W T 8 f% 16 FdK $?FlTW STJffiq 80% $$#TI 40% TJ V19R m $q 3'FllFl &FF $I 3rT rfftpl m&~93+rff-fi\3t;[atwmf@m$9311 wmti a=f$fmtti *W w $ m m m.rft Wl