Abstract
Thirty-two primiparous and 31 multiparous Alpine goats were used to determine influences of diets varying in level and source of forage on performance in early to mid-lactation for 16 wk.Diets consisted of 40％,50％,60％,and 70％forage(designated as 40F,50F,60F,and 70F,respectively)with 60F and 70F containing coarsely ground grass hay(primarily orchardgrass)and 40F and 50F containing cottonseed hulls,alfalfa pellets,and coarsely ground wheat hay.Diets contained 15.9％to 16.3％crude protein and 37.8％,42.1％,53.5％,and 55.4％neutral detergent fiber(NDF)with 10.0％,15.8％,50.1％,and 55.5％particle retention on a 19-mm sieve,and 26.1％,29.6％,38.3％,and 40.0％physically effective NDF(peNDF)for 40F,50F,60F,and 70F,respectively.Dry matter intake(2.71,2.75,1.96,and 1.95 kg/d)and milk yield(2.82,2.71,2.23,and 2.10 kg/d for 40F,50F,60F,and 70F,respectively)were lower(P＜0.05)for the two diets highest in forage.Digestion of organic matter was similar among diets(P＞0.05),but digestibility of NDF was greater(P＜0.05)for 60F and 70F(57.5％,58.4％,68.9％,and 72.2％for 40F,50F,60F,and 70F,respectively).Diet affected(P＜0.05)milk fat(3.16％,3.37％,2.93％,and 2.97％)and protein concentrations(2.62％,2.69％,2.58％,and 2.52％for 40F,50F,60F,and 70F,respectively).Milk energy yield was greater(P＜0.05)for the two diets lowest in forage(7.51,7.45,5.68,and 5.34 MJ/d),although yield relative to dry matter intake was not affected(P＞0.05)by diet and was lower(P＜0.05)for primiparous vs.multip-arous goats(2.71 and 3.09 MJ/kg).Ruminal pH and acetate proportion were greater for 60F and 70F than for the other diets and the proportion of butyrate was lower for the two diets highest in fiber.The mean lengths of time spent ruminating,eating,standing,and lying were not affected(P＞0.05)by diet or parity,but many interactions involving diet,period,hour,and parity were significant(P＜0.05).In conclusion,lactational performance of Alpine goats in early to mid-lactation will be constrained with diets high in forage of moderate quality,peNDF content,and large particle size,which appeared related to limited feed intake.
基金项目
USDA National Institute of Food and Agriculture,Evans-Allen Project OKLUGOETSCH2017(Accession Number 1012650)
Capacity Building Grant OKLU-PUCHALA2018(Accession Number 1018078)
USDA NIFA Evans-Allen Project OKLUWANG2023(Accession Number 7004023)
NETL
NSTL
万方数据