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The aim of this study was to investigate the effects of sex on the net requirements of growth for Ca (NCa), P (NP), Na (NNa), K (NK), and Mg (NMg) in Saanen goats from 5 to 45 kg BW, with or without consideration of the degree of maturity. A database containing 209 individual records for Saanen goats (69 castrated males, 71 intact males, and 69 females) was generated from 6 comparative slaughter studies. Total amounts of Ca, P, Na, K, and Mg in the body were fitted to logarithmized allometric equations using empty BW (EBW) or degree of maturity (EBW/mature EBW) as regressors. The equations were fitted using a mixed model, where sex was considered a fixed effect and study was considered a random effect. Net requirements were estimated by the first derivative of the logarithmized allometric equations. Then, a Monte Carlo simulation was used to assess the uncertainty of calculated net requirement values. Without considering the degree of maturity, sex did not affect NCa, NP, and NNa ( > 0.10). Conversely, considering the degree of maturity, NCa and NP of intact males were 5% and 2%, respectively, greater than those of castrated males and females ( 0.10), NK decreased by 26% (i.e., without considering the maturity degree) or 27% (i.e., considering the degree of maturity) from 5 to 45 kg BW. Therefore, the consideration of maturity stage highlights differences across sexes in the net macromineral requirements for growth in goats. Elucidation of sex effects on macromineral requirements for growth may be useful for improving the accuracy of recommendations for mineral requirements for dairy goats.

The aim of this study was to investigate the energy requirements of female and intact and castrated male Saanen goats. Animals were randomly assigned to 1 of 2 experiments designed to investigate the energy requirements for maintenance and gain. To determine the maintenance requirements, 85 goats were used (26 intact males, 30 castrated males, and 29 females) with an initial BW of 30.3 ± 0.87 kg. Thirty goats (8 intact males, 9 castrated males, and 13 females) were slaughtered to be used as the baseline group. The remaining goats were assigned in a split-plot design using a 3 × 3 factorial arrangement (3 sexes-intact males, castrated males, and females-and 3 DMI levels-ad libitum and restricted fed to 75 or 50% of the ad libitum intake). The NE was obtained using 65 goats (20 intact males, 22 castrated males, and 23 females) fed ad libitum in a completely randomized design. Eight intact males, 9 castrated males, and 13 females were slaughtered at 30.5 ± 1.53 kg BW. Seventeen goats (6 intact males, 6 castrated males, and 5 females) were slaughtered at 38.1 ± 0.49 kg BW. The remaining goats were slaughtered at 44.0 ± 0.50 kg BW. The NE did not differ between the sexes ( = 0.59; 258.5 kJ/kg BW), resulting in a ME for maintenance of 412.4 kJ/kg BW. The estimated energy use efficiency for maintenance was 0.627. During the growth phase, NE differed between the sexes ( < 0.001); intact males, castrated males, and females showed an average NE equal to 15.2, 18.6, and 22.7 MJ/kg of empty weight gain, respectively. The energy requirements for growth differed between the sexes. The difference was found to be due to distinct NE and partial efficiency of ME utilization for growth in intact and castrated males and females during the late growth phase. This study may contribute to adjustments in feeding system energy recommendations regarding the NE and NE found for goats during the late growth phase.