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Differences and/or similarities in the influence of sex class for hair sheep requirements remain inconclusive. Knowledge of energy requirements allows well-formulated diets to be provided which is crucial for improving animal production. We aimed to determine the effect of sex class on the net energy requirements of growing hair sheep in a multi-study approach. We used a data set composed of individual measurements of 382 hair sheep (299 non-castrated and 83 castrated males) from 11 studies that used the methodology of comparative slaughter. Net energy requirements for maintenance (NEm) were obtained by the regression between heat production and metabolizable energy intake. The metabolizable energy requirements for maintenance (MEm) were calculated by the iterative method, and the efficiency of use of metabolizable energy for maintenance (km) was obtained by NEm divided by MEm. The net energy requirements for gain (NEg) were estimated from retained energy (RE) against empty BW gain (EBWG). The efficiency of energy use for weight gain (kg) was obtained from the relationship between RE and the energy metabolizable intake for gain, removing the intercept. There was an effect of sex on NEg and two equations were generated: NEg (MJ/day) = 1.040 (±0.04055) × EBW0.75 × EBWG0.8767(±0.03293) and NEg (MJ/day) = 1.040 (±0.04055) × EBW0.75 × EBWG0.8300(±0.03468) (R2 = 0.86; MSE = 0.0037; AIC = -468.0) for non-castrated and castrated males, respectively. Sex class did not affect kg (P > 0.05) and one kg was generated (0.29). Sex did not affect kprotein (P = 0.14) and kfat (P = 0.32), assuming an average deposition efficiency of 0.27 for protein and 0.78 for fat. The NEm and MEm did not differ (P > 0.05) between sex classes, with a value of 0.272 and 0.427 MJ/kg0.75 EBW per day, respectively. The km observed was 0.64. In conclusion, non-castrated and castrated male hair sheep have similar maintenance energy requirements although energy requirements for gain differed among them. The Committees overestimate the gain and maintenance requirements for hair sheep. Therefore, the equations generated in this study are recommended.

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The reticulorumen (RR) fractional passage rate (kp; /h) of particles and solutes plays an important role in fiber digestion, methane production, and microbial yield. However, none of the available models for predicting RR kp consider individuals' characteristics of growing goats. The objective was to develop empirical models for predicting the RR kp of particles and solutes in growing goats. Our database involved 175 individual records of castrated males (n = 61), females (n = 57), and intact males (n = 57) growing Saanen goats fed ad libitum, 75% or 50% of ad libitum. Goats were slaughtered around 15, 22, 30, 37, or 45 kg BW. We used Akaike's information criterion to select the best prediction models. We evaluated the predictive ability of these models using Lin's concordance correlation coefficient (CCC) and RMSE of prediction (RMSPE) in a 4-fold cross-evaluation. The DM intake (DMI; kg/day), potentially digestible NDF intake (pdNDFI) level (g/kg BW), and RR wet pool size (kg) demonstrated similar importance in predicting RR kp of solutes (CCC = 0.59; RMSPE = 0.050 /h or 34.43%). However, when RR wet pool size was not included in the model, RR kp of solutes could still be precisely and accurately predicted using only DMI level (g/kg BW) (CCC = 0.47; RMSPE = 0.053 /h or 36.58%). The RR wet tissues and wet pool size (kg), NDF intake (NDFI) (kg/day), and indigestible NDFI (iNDFI):NDFI ratio were important predictors of RR kp of particles (CCC = 0.51; RMSPE = 0.0064 /h or 25.43 %). However, when RR wet tissues and wet pool size were not included in the model, iNDFI:NDFI ratio, NDFI level (g/kg BW), and RR kp of solutes presented greater importance in predicting RR kp of particles (CCC = 0.20; RMSPE = 0.0074 /h or 29.55%). Sex was not a significant predictor variable for the selected models. In summary, the RR kp of solutes was more dependent on feed intake level while the RR kp of particles was more dependent on diet composition and RR kp of solutes. Our models were precise and accurate for predicting RR kp of solutes (CCC = 0.57 and 0.47; RMSPE = 0.051 and 0.054 /h) and particles (CCC = 0.48 and 0.17; RMSPE = 0.0066 and 0.0076 /h) after cross-evaluation. This suggests that our models can be integrated into feeding systems with mechanistic approaches that simulate other reticulorumen functions, such as digestion, microbial growth, and methane emission.

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Goat genotype may alter the net energy and protein requirements for maintenance (NEm and NPm, respectively) and weight gain (NEg and NPg).This study was designed to investigate and quantify the effect of goat type on NEm, NPm, NEg and NPg, and quantify the net requirements for energy and protein for dairy, meat and indigenous growing male goats. For that, comparative slaughter studies were gathered and a meta-analytical approach was used. Two distinct databases were organized: one composed of 233 individual records from 11 studies of meat (n = 81), dairy (n = 97) and indigenous (n = 55) growing male goats weighing from 4.50 to 51.0 kg, to depict NEm and NPm; and another database composed of 239 individual records from nine studies of meat (n = 87), dairy (n = 97) and indigenous (n = 55) growing male goats weighing from 4.30 to 51.0 kg, to depict NEg and NPg. Our findings showed that NEm of meat goats was 8.5% greater (336 ± 10.8 kJ/kg0.75 of empty BW; EBW) than dairy and indigenous goats (310 ± 8.20 kJ/kg0.75 EBW; P < 0.05). Whereas, NPm was not affected by goat type (1.92 ± 0.239 g/kg EBW; P = 0.91). The NPg was 185.1 ± 1.82 g/kg of EBW gain for goats weighing 5 kg BW and 192.5 ± 4.33 g/kg of EBW gain for goats weighing 45 kg BW, and thus did not change across goat type (P = 0.12). On the other hand, NEg increased from 7.29 ± 0.191 to 11.9 ± 0.386 MJ/kg of EBW in male dairy goats, and from 7.32 ± 0.144 to 15.7 ± 0.537 MJ/kg of EBW in meat and indigenous growing male goats weighing between 5 and 45 kg BW. When body protein was used as a predictor in the allometric equation instead of EBW seeking to account for the degree of maturity, goat type differences disappeared; however, this predictor showed a high variation among individuals. In conclusion, energy and protein requirements for gain in distinct goat types reflect on body composition differences. Future research should focus on better understanding the maturity degree and its consequences in the energy requirement of growing male goats and better depict the goat type effect on it, as well as on the efficiency of utilization.

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The aim of this study was to investigate the effects of sex on the requirements for maintenance and efficiency of energy utilization in growing Saanen goats. A database from 7 comparative slaughter studies that included 238 Saanen goats was gathered to provide information for the development of prediction equations of energy requirements for maintenance and efficiency of energy utilization. The experimental design provided different levels of metabolizable energy intake (MEI) and empty body weight (EBW). The data were analyzed so that sex (e.g., intact males, castrated males, and females; n = 98, 80, and 60, respectively) was a fixed effect, and blocks nested in the studies and goat sex were random effects. For the development of linear and nonlinear equations, we used the MIXED and NLMIXED procedures in SAS (SAS Institute Inc., Cary, NC). Nonlinear regression equations were developed to predict heat production (HP, kcal/kg0.75 of EBW; dependent variable) from MEI (kcal/kg0.75 of EBW; independent variable). Using the comparative slaughter technique, the net energy requirement for maintenance (NEM) was calculated as the value of HP at MEI equal to zero. Additionally, NEM was evaluated based on the degree of maturity. The metabolizable energy requirement for maintenance was calculated as the value at which HP is equal to MEI. Efficiency of ME utilization for maintenance (km) was calculated as the ratio between NEM and the metabolizable energy requirement for maintenance. Efficiency of energy utilization for growth (kg) was assumed to be the slope of the linear regression of retained energy (RE) on MEI above the maintenance stage (model intercept equal to 0). Efficiencies of RE as protein (kp) and as fat (kf) were calculated using the multiple linear regression of MEI above the maintenance (model intercept equal to 0) on RE as protein and as fat, respectively. Sex affected NEM (75.0 ± 1.76 kcal/kg0.75 of EBW for males and 63.6 ± 2.89 kcal/kg0.75 of EBW for females) and sex did not affect km (0.63). In contrast, sex no longer affected NEM when degree of maturity was considered on its estimation. The kg was different between sexes (0.31 for castrated males and females, and 0.26 for intact males), but kp (0.21) and kf (0.80) were similar between sexes. These results may be useful for improving robustness of the energy requirement recommendations for dairy goats.

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Requirements for growth in the different sexes remain poorly quantified in goats. The objective of this study was to develop equations for estimating net protein (NPG) and net energy (NEG) for growth in Saanen goats of different sexes from 5 to 45 kg of body weight (BW). A data set from 7 comparative slaughter studies (238 individual records) of Saanen goats was used. Allometric equations were developed to determine body protein and energy contents in the empty BW (EBW) as dependent variables and EBW as the allometric predictor. Parameter estimates were obtained using a linearized (log-transformation) expression of the allometric equations using the MIXED procedure in SAS software (SAS Institute Inc., Cary, NC). The model included the random effect of the study and the fixed effects of sex (intact male, castrated male, and female; n = 94, 73, and 71, respectively), EBW, and their interactions. Net requirements for growth were estimated as the first partial derivative of the allometric equations with respect to EBW. Additionally, net requirements for growth were evaluated based on the degree of maturity. Monte Carlo techniques were used to estimate the uncertainty of the calculated net requirement values. Sex affected allometric relationships for protein and energy in Saanen goats. The allometric equation for protein content in the EBW of intact and castrated males was log10 protein (g) = 2.221 (±0.0224) + 1.015 (±0.0165) × log10 EBW (kg). For females, the relationship was log10 protein (g) = 2.277 (±0.0288) + 0.958 (±0.0218) × log10 EBW (kg). Therefore, NPG for males was greater than for females. The allometric equation for the energy content in the EBW of intact males was log10 energy (kcal) = 2.988 (±0.0323) + 1.240 (±0.0238) × log10 EBW (kg); of castrated males, log10 energy (kcal) = 2.873 (±0.0377) + 1.359 (±0.0283) × log10 EBW (kg); and of females, log10 energy (kcal) = 2.820 (±0.0377) + 1.442 (±0.0281) × log10 EBW (kg). The NEG of castrated males was greater than that of intact males and lower than that of females. Using degree of maturity for estimating NPG and NEG, we could remove the differences between sexes. These results indicate that NPG and NEG differ among sexes in growing Saanen goats, and this difference should be accounted for by feeding systems. Including the degree of maturity as predictor cancels out those differences across sexes in protein and energy requirements.

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Mineral requirements of pregnant dairy goats are still not well defined; therefore, we investigated the net Ca, P, Mg, Na and K requirements for pregnancy and for maintenance during pregnancy in two separate experiments. Experiment 1 was performed to estimate the net Ca, P, Mg, Na and K requirements in goats carrying single or twin fetuses from 50 to 140 days of pregnancy (DOP). The net mineral requirements for pregnancy were determined by measuring mineral deposition in gravid uterus and mammary gland after comparative slaughter. In total, 57 dairy goats of two breeds (Oberhasli or Saanen), in their third or fourth parturition, were randomly assigned to groups based on litter size (single or twin) and day of slaughter (50, 80, 110 and 140 DOP) in a fully factorial design. Net mineral accretion for pregnancy did not differ by goat breed. The total daily Ca, P, Mg, Na and K requirements for pregnancy were greatest in goats carrying twins (P<0.05), and the requirements increased as pregnancy progressed. Experiment 2 was performed to estimate net Ca, P, Mg, Na and K requirements for dairy goat maintenance during pregnancy. In total, 58 dairy goats (Oberhasli and Saanen) carrying twin fetuses were assigned to groups based on slaughter day (80, 110 and 140 DOP) and feed restriction (ad libitum, 20% and 40% feed restriction) in a randomized block design. The net Ca, P and Mg requirements for maintenance did not vary by breed or over the course of pregnancy. The daily net requirements of Ca, P and Mg for maintenance were 60.4, 31.1 and 2.42 mg/kg live BW (LBW), respectively. The daily net Na requirement for maintenance was greater in Saanen goats (11.8 mg/kg LBW) than in Oberhasli goats (8.96 mg/kg LBW; P<0.05). Daily net K requirements increased as pregnancy progressed from 8.73 to 15.4 mg/kg LBW (P<0.01). The findings of this study will guide design of diets with adequate mineral content for pregnant goats throughout their pregnancy.

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The current mineral requirements for growing goat kids are based on sheep and cattle studies without differentiating between the stages of development or gender. The aims of this study were to determine the net requirements for growth of Ca, P, Mg, Na and K of Saanen goat kids during the initial stages of growth and to analyse the effect of gender on the net requirements for growth of these macrominerals. Eighteen female, 19 intact male and 10 castrated male Saanen goat kids were studied. The kids were selected applying a completely randomized design and slaughtered when their body weight (BW) reached approximately 5, 10 and 15 kg to determine the mineral requirements for growth at these stages. The net mineral requirements for growth were similar among genders. The goat kids had slightly increased net requirements of Ca, P and Mg for growth with increasing BW from 5 to 15 kg. The net requirements for growth of Ca, P, Mg, Na and K ranged from 9.61 to 9.67 g/kg of BW gain, 7.14 to 7.56 g/kg of BW gain, 0.34 to 0.37 g/kg of BW gain, 1.26 to 1.13 g/kg of BW gain, 1.88 to 1.82 g/kg of BW gain as the animals grew from 5 to 15 kg respectively. In conclusion, when formulating diets for Saanen goat kids in early growth stage mineral levels do not need to adjusted based on gender.

Assuntos

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The objective of this research was to estimate the energy and protein requirements for maintenance and growth in male (castrated and intact) and female Saanen goat kids between 15 and 30 kg BW. To determine the net energy requirements for maintenance (NEm ) and the net protein requirements for maintenance (NPm ), 75 goats (25 castrated and 26 intact males and 24 females) were used. Twenty-one goats (seven castrated and eight intact males and six females) were randomly assigned for slaughter to estimate the initial empty body composition. The 54 remaining animals (18 castrated and 18 intact males and 18 females) were randomly assigned in a split-plot design using a 3 × 3 factorial arrangement with three sexes and three levels of intake (ad libitum and restricted feed to 75% or 50% of the ad libitum intake). Within each sex, six blocks (three goats per block) were formed and one goat was randomly assigned to each level of intake. The 75% and the 50% of ad libitum rationing were determined daily, based on the DMI of the animal fed ad libitum on the previous day. All animals within block were slaughtered when the animal fed ad libitum reached 30 kg BW. The net energy requirements for gain (NEg ) and the net protein requirements for gain (NPg ) were obtained using 58 animals (20 castrated and 20 intact males and 18 females). The animals were fed ad libitum and slaughtered at targeted BW (15, 23 or 30 kg). Sex did not affect NEg and NPm (277.8 kJ/kg0.75  BW day and 2.98 g CP/kg0.75  BW day respectively), as well as NPg (180.9 ± 6.48 g/kg EBW gain) in Saanen goat kids. However, castrated males and females had similar NEg (varied from 12.6 ± 0.424 to 17.9 ± 1.38 MJ/kg EBW gain), greater than intact males (varied from 9.74 ± 0.420 to 10.7 ± 0.984 MJ/kg EBW gain), as the BW increased from 15 to 30 kg.

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The aim of this study was to investigate the effects of different levels of soya bean oil in the total diet on the growth rate, metabolic changes, and oestrogen and progesterone release in Saanen goats. After dietary adaptation, 21 prepubertal goats (weight of 29.12 ± 0.91 kg, 230 days old) were randomly distributed among three diets of D2: inclusion of 2% soya bean oil in the total diet; D3: basal diet - inclusion of 3% soya bean oil in the total diet; and D4: inclusion of 4% soya bean oil in the total diet. The basal diet (D3) was formulated to promote a daily gain of 0.140 kg. The goats were weighed, and their blood samples were collected weekly. Glucose, cholesterol, triglycerides, total protein, urea, non-esterified fatty acids, beta-hydroxybutyrate, oestrogen and progesterone in the plasma were measured. Prepubertal goats that were fed D4 exhibited a significantly lower dry matter intake, urea and cholesterol levels compared with the goats that were fed D2 and D3. Indeed, goats that were fed D4 displayed a significantly lower final weight than goats that were fed D2 and D3. In contrast, the inclusion of soya bean oil in the diet increased the progesterone and oestrogen concentrations, and goats that were fed D4 released a significantly higher concentration of progesterone than those that were fed D2 and D3. Furthermore, the percentage of goats with a progesterone level greater than 1 ng/ml (functional Corpus luteum) was significantly higher among the goats that were fed D3 and D4 than among those that were fed D2. In this study, although the inclusion of 4% soya bean oil in the diet decreased dry matter intake and growth rate, it increased progesterone concentration and the percentage of goats with a functional Corpus luteum, suggesting that the inclusion of soya bean oil accelerated puberty in prepubertal goats.

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Previous research on energy requirements of female Saanen goats, using the factorial approach, has not considered the specific requirements for maintenance and growth during the pubertal phase. Thus, the purpose of this study was to estimate energy requirements for maintenance (Trial 1) and growth (Trial 2) of non-pregnant and non-lactating female Saanen goats at the pubertal phase from 30 to 45 kg. In Trial 1, the net energy requirements for maintenance (NEm ) were estimated using 18 female Saanen goats randomly assigned to three levels of intake: ad libitum, and 70% and 40% of ad libitum intake. These animals were pair-fed in six slaughter groups, each consisting of one animal for each level of intake. In Trial 2, the net energy requirements for growth (NEg ) were estimated using 18 female Saanen goats, which were fed ad libitum and slaughtered at targeted BW of 30, 38 and 45 kg. The NEm was 52 kcal/kg(0.75) of BW. The NEg increased from 3.5 to 4.7 Mcal/kg of BW gain as BW increased from 30 to 45 kg. Our results suggest that the guidelines of the major feeding systems for the entire growth phase may not be adequate for females at pubertal phase.

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The objective of this study was to estimate genetic parameters for 305-day cumulative milk yield (MY305) and its association with test-day milk yield (TDMY) in Saanen and Alpine goats in order to provide information that allows the use of TDMY as selection criteria. This was done using standard multi-trait and reduced rank models. Data from 1157 lactations, including the first three kiddings, and 5435 test-day records from 683 Saanen and 449 Alpine goats were used. MY305 was analyzed together with TDMY by multi-trait analysis, from the first to tenth test-day, using records of the first three lactations as repeated measures. Three multi-trait models were used: a standard (SM) and two reduced rank models that fitted the first two (PC2) and three (PC3) genetic principal components. Akaike and Schwarz Bayesian information criteria were used to compare models. Heritability for TDMY estimated with the SM ranged from 0.20 to 0.66, whereas the range calculated from the PC2 model was 0.16 to 0.63. Genetic correlations between TDMY and MY305 were positive and moderate to high, ranging from 0.56 to 0.98 when estimated with the SM, and 0.91 to 1.00 when estimated with the PC2. The standard multi-trait model produced estimates that were more accurate than the reduced rank models. Although the SM provided the worst fit according to the two model selection criteria, it was the best in this dataset.

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The aim of study was to determine the energy requirements for maintenance and growth of forty-one Saanen, intact male kids with initial body weight (BW) of 5.12±0.19 kg. The baseline (BL) group consisted of eight kids averaging 5.46±0.18 kg BW. An intermediate group consisted of six kids, fed for ad libitum intake, that were slaughtered when they reached an average BW of 12.9±0.29 kg. The remaining kids (n = 27) were randomly allocated into nine slaughter groups (blocks) of three animals distributed among three amounts of dry matter intake (DMI; ad libitum and restricted to 70% or 40% of ad libitum intake). Animals in a group were slaughtered when the ad libitum-treatment kid in the group reached 20 kg BW. In a digestibility trial, 21 kids (same animals of the comparative slaughter) were housed in metabolic cages and used in a completely randomized design to evaluate the energetic value of the diet at different feed intake levels. The net energy for maintenance (NEm) was 417 kJ/kg(0.75) of empty BW (EBW)/d, while the metabolizable energy for maintenance (MEm) was 657 kJ/kg(0.75) of EBW/d. The efficiency of ME use for NE maintenance (km) was 0.64. Body fat content varied from 59.91 to 92.02 g/kg of EBW while body energy content varied from 6.37 to 7.76 MJ/kg of EBW, respectively, for 5 and 20 kg of EBW. The net energy for growth (NEg) ranged from 7.4 to 9.0 MJ/kg of empty weight gain by day at 5 and 20 kg BW, respectively. This study indicated that the energy requirements in goats were lower than previously published requirements for growing dairy goats.

RESUMO

Advances in mineral nutrition of goats have been made during the last decade, especially in our understanding of Ca and P requirements. However, few studies have focused on the mineral requirements of crossbred Boer goats in their growth phase. Our objective for this study was to determine the macromineral (Ca, P, Mg, K, and Na) requirements for the maintenance and growth of intact, male three-fourths Boer × one-fourth Saanen kids (n = 34; 20.5 ± 0.24 kg of initial BW). Two trials were conducted: 1 for maintenance and 1 for growth requirements. In the maintenance trial, 28 kids were used. The baseline (BL) group consisted of 7 randomly selected kids averaging 21.2 ± 0.36 kg BW and 122 d old. The remaining kids (n = 21; age 168 ± 5 d) were randomly allocated into 7 slaughter groups (blocks) including 3 animals distributed among 3 amounts of DMI (treatments: ad libitum and restricted to 70 or 40% of ad libitum intake). Animals in a group were slaughtered when the ad libitum-treatment kid in the block reached 35 kg BW. The BL and ad libitum-fed groups in the maintenance trial were also part of the growth trial. Therefore, in the growth trial, 20 kids fed for ad libitum intake were used as follows: 7 kids slaughtered at 21.2 ± 0.36 kg BW (BL), 6 kids slaughtered at 28.2 ± 0.39 kg BW (intermediate slaughter), and 7 kids slaughtered at 35.6 ± 0.36 kg BW. Empty whole bodies of the kids (head + feet, hide, internal organs + blood, and carcass) were weighed, ground, mixed, and subsampled for chemical analyses. Daily maintenance requirements, calculated using the comparative slaughter technique (P < 0.001), were estimated as 32.3 ± 1.1 mg Ca, 30.8 ± 1.2 mg P, 1.31 ± 0.5 mg Mg, 8.41 ± 3.0 mg K, and 5.14 ± 1.0 mg Na/kg of empty BW (EBW). Net requirements for growth increased from 6.2 to 6.6 g Ca, 5.3 to 5.4 g P, and 0.29 to 0.30 g Mg and decreased from 1.20 to 1.07 g K and 0.65 to 0.59 g Na/kg of EBW gain for kids from 20 to 35 kg BW. This study indicated that the net mineral requirements for Boer crossbred goat kids may be different from those of purebred or other genotypes, and more data are needed for goats in general.

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Meat production by goats has become an important livestock enterprise in several parts of the world. Nonetheless, energy and protein requirements of meat goats have not been defined thoroughly. The objective of this study was to determine the energy and protein requirements for maintenance and growth of 34 (3/4) Boer x (1/4) Saanen crossbred, intact male kids (20.5 +/- 0.24 kg of initial BW). The baseline group was 7 randomly selected kids, averaging 21.2 +/- 0.36 kg of BW. An intermediate group consisted of 6 randomly selected kids, fed for ad libitum intake, that were slaughtered when they reached an average BW of 28.2 +/- 0.39 kg. The remaining kids (n = 21) were allocated randomly on d 0 to 3 levels of DMI (treatments were ad libitum or restricted to 70 or 40% of the ad libitum intake) within 7 slaughter groups. A slaughter group contained 1 kid from each treatment, and kids were slaughtered when the ad libitum treatment kid reached 35 kg of BW. Individual body components (head plus feet, hide, internal organs plus blood, and carcass) were weighed, ground, mixed, and subsampled for chemical analyses. Initial body composition was determined using equations developed from the composition of the baseline kids. The calculated daily maintenance requirement for NE was 77.3 +/- 1.05 kcal/kg(0.75) of empty BW (EBW) or 67.4 +/- 1.04 kcal/kg(0.75) of shrunk BW. The daily ME requirement for maintenance (118.1 kcal/kg(0.75) of EBW or 103.0 kcal/kg(0.75) of shrunk BW) was calculated by iteration, assuming that the heat produced was equal to the ME intake at maintenance. The partial efficiency of use of ME for NE below maintenance was 0.65. A value of 2.44 +/- 0.4 g of net protein/kg(0.75) of EBW for daily maintenance was determined. Net energy requirements for growth ranged from 2.55 to 3.0 Mcal/kg of EBW gain at 20 and 35 kg of BW, and net protein requirements for growth ranged from 178.8 to 185.2 g/kg of EBW gain. These results suggest that NE and net protein requirements for growing meat goats exceed the requirements previously published for dairy goats. Moreover, results from this study suggest that the N requirement for maintenance for growing goats is greater than the established recommendations.

Assuntos