大麦粉碎粒度对育肥湖羊生长育肥性能和养分消化及肉品质的影响

Effects of barley particle size in diets on growth performance,nutrient digestion,and meat quality of fattening Hu sheep

为研究饲粮中大麦(Hordeum vulgare)粉碎粒度对育肥湖羊生长性能、养分消化、瘤胃液挥发性脂肪酸、屠宰性能和肉品质的影响,本研究选取54只3月龄湖羊公羔(初始体重为29.85±0.23 kg),随机分为3个处理,每个处理18个重复,每个重复1只羊。3个处理分别为整粒大麦经过2、3和4 mm的筛片孔径粉碎,即小粉碎粒度(small particle size,SPS)组、中粉碎粒度(middle particle size,MPS)组和大粉碎粒度(large particle size,LPS)组。整个试验期包括:适应期14 d,预饲期7 d,正试期63 d。结果表明:1)各处理末重、干物质采食量(dry matter intake,DMI)、平均日增重(average daily growth,ADG)和料重比(feed to gain ratio,F/G)无显著差异(P>0.05)。2)大麦粉碎粒度对干物质(dry matter,DM)、有机物(organic matter,OM)和粗蛋白(crude protein,CP)消化率无显著影响(P>0.05),但中性洗涤纤维(neutral detergent fiber,NDF)和酸性洗涤纤维(acid detergent fiber,ADF)表观消化率受大麦粉碎粒度的显著影响(P<0.05)。LPS组NDF消化率较SPS和MPS组显著提高了14.3%和7.8%(P<0.05)。LPS组ADF表观消化率较SPS组显著提高了22.1%(P<0.05),LPS和MPS组之间无显著差异(P>0.05)。3)各处理总挥发性脂肪酸(total volatile fatty acid,TVFA)、乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸含量均无显著差异(P>0.05),乙酸∶丙酸和瘤胃液pH也无显著差异(P>0.05)。4)各处理宰前活重、胴体重、屠宰率及瘤胃腹囊和背囊的亮度、红度和黄度均无显著差异(P>0.05)。5)各处理0和24 h pH、滴水损失、失水率和肌肉亮度、红度、黄度均无显著差异(P>0.05),但LPS组剪切力显著高于SPS和MPS组(P<0.05)。在本研究饲粮配方下,大麦粉碎粒度未对育肥湖羊的生长性能、屠宰性能和瘤胃液挥发性脂肪酸产生影响,但大麦4 mm粉碎处理对育肥湖羊的表观消化率影响效果最佳,有提高纤维消化的作用。

The purpose of this study was to determine the effect of barley particle size in diets on growth performance,nutrient digestion,rumen fluid volatile fatty acids,slaughter performance,and meat quality of fattening Hu sheep.Fifty-four healthy,male(approximately 29.85±0.23 kg)Hu lambs were randomly divided into three treatment groups,each treatment was replicated eighteen times with the sheep being the experimental unit.The three treatments consisted of whole barley that had been ground and passed through a 2 mm sieve[small particle size group(SPS group)],3 mm sieve[middle particle size group(MPS group)],and a 4 mm sieve[large particle size group(LPS group)].The trial period included a fourteen-day adaptation period,a seven-day pre-feeding period,and a sixty-three-day formal period.The results showed that:1)There was no significant difference in the final weight,dry matter intake(DMI),average daily weight gain(ADG),and feed to gain ratio(F/G)among the treatments(P>0.05).2)There were no significant differences in dry matter(DM),organic matter(OM),and crude protein(CP)digestibilities among the treatments(P>0.05),but the apparent digestibilities of neutral detergent fiber(NDF)and acid detergent fiber(ADF)were significantly different(P<0.05).The apparent digestibility of NDF in the LPS group was 14.3 and 7.8%higher than in the SPS and MPS groups,respectively(P<0.05).The apparent digestibility of ADF in the LPS group was 22.1%higher than that of the SPS group and comparable to that of the MPS group.3)The total volatile fatty acid(TVFA),acetic acid,propionic acid,isobutyric acid,butyric acid,isovaleric acid,and valeric acid were not significantly affected by the treatments(P>0.05).Similarly,the acetic to propionic acid ratio and rumen fluid pH were not significantly affected by the treatments(P>0.05).4)There were no significant differences in live weight before slaughter,carcass weight,dressing percentage and brightness,redness,and yellowness of the rumen ventral sac and dorsal sac among treatments(P>0.05).5)There were no significant differences in pH,drip loss,water loss rate,muscle brightness,redness,and yellowness at 0 and 24 h post-slaughter among the treatments(P>0.05);however,the shearing force in the LPS group was significantly higher than that in the SPS and MPS groups(P<0.05).In summary,barley particle size in diets does not affect the growth performance,slaughter performance,and volatile fatty acids in the rumen fluid of fattening Hu sheep;however,the apparent digestibility of the LPS group was significantly affected,which might indicate improvement in fiber digestibility.