Energy and protein requirements for maintenance of dairy goats during pregnancy and their efficiencies of use1

Abstract

It has been suggested that maintenance requirements are similar among animals of different physiological stages; however, important physiological changes occur in the maternal body during pregnancy. Therefore, the aim of this study was to determine the energy and protein requirements for the maintenance of pregnant dairy goats and to estimate their efficiency of energy and protein utilization for maintenance and pregnancy. We used 66 multiparous pregnant goats having 49.0 ± 1.59 kg initial BW (around the third or fourth parturition) arranged in a randomized block design with a 3 × 3 factorial scheme including slaughter at different days of pregnancy (DOP; 80, 110, and 140 d) and feed restriction (0, 20, and 40% feed restriction). The comparative slaughter technique was used to estimate energy and protein maintenance requirements. Goats slaughtered at 140 DOP were subjected to digestibility trials at around 80, 110, and 140 DOP to estimate diet metabolizability and N balance (NBAL). Metabolizability decreased with feed restriction and was 63.3 ± 2.16, 55.7 ± 2.35, and 58.2 ± 2.30% at 0, 20, and 40% of feed restriction, respectively ( < 0.01). There was no effect of DOP on NE or the requirements of ME for maintenance (ME), which were 197 and 315 kJ/kg empty body weight (EBW), respectively, and the efficiency of ME utilization for maintenance (k) was 0.63. Similarly, DOP did not affect thedaily net protein requirements for maintenance (NP) estimated using the comparative slaughter technique (1.38 ± 0.512 g/kg EBW; = 0.003) or the NP estimated using NBAL (2.49 ± 0.594 g/kg EBW; < 0.01). The MP requirement for maintenance (MP) estimated using the comparative slaughter technique was not affected by DOP and was 3.22 g MP/kg EBW ( < 0.01). The efficiency of MP utilization for maintenance (k) was 0.43. The efficiency of ME utilization for pregnancy (k) increased with the progress of pregnancy and was 0.058, 0.10, and 0.19 at 80, 110, and 140 DOP, respectively. Similarly, the efficiency of MP utilization for pregnancy (k) increased with DOP and was 0.12, 0.21, and 0.43 at 80, 110, and 140 DOP, respectively. There was no evidence that pregnancy affected NE, ME, NP, and MP or k and k, which were also unaffected by DOP. However, k and k increased with pregnancy progress as a response to the physiological changes that pregnant females are subjected to.

Metabolizable Protein: 2. Requirements for Maintenance in Growing Saanen Goats

“…The NP M obtained using the comparative slaughter technique is similar to the values obtained by the independent studies used in this dataset, as expected, in a study evaluating goat kids [1.32 g/kg 0.75 BW in Saanen kids from 5 to 20 kg of BW; ( 9 )], as well as in late growth goats [1.46 g/kg 0.75 BW in Saanen goats from 30 to 45 kg BW; ( 5 )]. The age seems not to affect the protein requirements for maintenance, similar to that previously described in pregnant dairy goats [1.38 g/kg 0.75 EBW; ( 7 )].…”

“…Estimates of NP M by the comparative slaughter technique yielded more precise equations than those obtained from the N balance data, which can be verified by the dispersion of the points in the graphs presented herein and in the residual analysis. Similarly, in pregnant goats, a low error was also reported using the comparative slaughter technique, where this approach possibly gave a more reliable reference value in mature goats ( 7 ). Slaughter studies are costly, but they indicate a more reliable measure of protein retention ( 2 ).…”

“…The estimates of NP M obtained using the comparative slaughter technique were ~50% lower than those obtained using the N balance method. It has been reported that N balance overestimates the values and results in a greater variation for the protein requirements for maintenance ( 5 , 7 ). The overall value using the comparative slaughter technique was lower than that reported by AFRC [( 4 ); 2.19 g/kg 0.75 BW of NP M ], where the system adopted a k PM of 1.0 to maintenance.…”

Moringa oleifera Supplementation Improves Antioxidant Status and Biochemical Indices by Attenuating Early Pregnancy Stress in Beetal Goats

“…Therefore, the small ruminants are mainly kept on conventional grazing pastures, low-quality hay, and crop byproducts. These feedstuffs lack an adequate amount of protein, vitamins, and minerals to fulfill the nutritional requirements of pregnant goats (6). Maternal malnutrition has a negative impact on the conception rate and also adversely affects the fetus growth (7).…”

Applying the California net energy system to growing goats1

“…Even though the studies used in the meta-analysis covered goats from approximately birth to 18 mo old ( Figure 2 ), an effect of age in the NE m was not observed. On the other hand, Harter et al (2017) , in a comparative slaughter study with adult female goats (i.e., approximately 4 yr old), estimated NE m as 47.1 kcal/kg 0.75 EBW, which was 26% lower than NE m reported for growing female goats ( Souza, 2017 ), suggesting a decrease in NE m when goats are older than 18 mo old.…”