| Crop straw is a common of roughage resources,which containing the fibrous material could be digested and utilized by rumen microorganisms to provide energy for ruminants,but less 50% of the energy could be digested and utilized by the animal.The enzyme and oregano oil mainly improve the feed conversion ratio of the roughage diet by changing the rumen microbial population,hydrolyzing the lignocellulosic structure and inhibiting the proliferation of harmful microbial.The aim of this study was to estimate the effect of different straw sources supplementation with enzyme or oregano oil in the dietary on performances of Hu sheep,which provided the theoretical instruction and scientific basis for efficient production of forage diets.This study were divided into two sections:The first experiment aimed to determine the straw sources and enzyme on growth performance,nutrient digestibility,blood biochemical parameters and rumen microflora of Hu sheep.The experiment adopted a 2×2 factorial arrangement.Corn stover or wheat strawbased diets were formulated with or without enzyme(0% or 0.30%).A total of 60 twomonth-old healthy Hu sheep(29.49±0.33 kg)were assigned to four dietary treatments,with fifteen replicates in each treatment and a sheep in each replicates.The trial period was 84 days,which included 14 d for the transition test period,7 d for the preliminary test period and 63 d for the formal trial period.The results were shown as follow:1.There were no significant differences in body weight,DMI,ADG and F/G all groups of 1~21 d and 22~42 d(P>0.05).There were significantly increased in body weight and average daily gain among enzyme addition groups of 43~63 d(P<0.05).However,the dry matter intake and feed to gain were no significant difference between the treatments(P>0.05).The enzyme supplementation in diets with different straw source had the difference feed to gain among group during formal trial period(P<0.05),but have no effect on the average daily gain,dry matter intake,carcass weight,tail fat weight,dressing percentage in each group(P>0.05);2.There were significantly increased the apparent digestibility of dry matter and organic matter in enzyme addition groups(P<0.05).The apparent digestibility of organic matter in corn straw group were significantly higher that in wheat straw group(P<0.05).There were no significant differences in the apparent of crude protein and nitrogen metabolism in each group(P>0.05);3.The enzyme supplementation in diets with different straw source had no significant difference on the concentrations of TP,ALB,GLO,ALT,AST,ALP,LDH,UN,and TG(P>0.05),but were significantly increased the concentrations of GLU in enzyme treatments groups(P<0.05).The concentrations of CHO of sheep fed corn straw-based diets were significantly higher than that of sheep fed wheat straw-based diets(P<0.05);4.Adding enzyme significantly affect the concentrations of total volatile fatty acid(P<0.05),but the concentrations of acetate,propionate,valerate,isovalerate and acetate to propionate were not significantly difference in each group(P>0.05).The concentrations of butyrate of sheep fed corn straw-based diets were significantly higher than that of sheep fed wheat straw-based diets(P<0.05).There were significantly increased the number of Selenomonas ruminantium in the enzyme addition groups(P<0.05),and the number of Fibrobacter succinogenes was increased(P<0.10).The number of Ruminococcus albus and Fibrobacter succinogenes of sheep fed wheat straw-based diets were significantly higher than that of sheep fed corn straw-based diets(P<0.05).The second experiment aimed to determine the straw sources adding oregano oil on growth performance,nutrient digestibility,blood biochemical parameters and rumen microflora of Hu sheep.The experiment adopted a 2×2 factorial arrangement.Corn stover or wheat strawbased diets were formulated with or without oregano oil(0% or 0.25%).A total of 60 two-month-old healthy Hu sheep(29.33±0.29 kg)were assigned to four dietary treatments.Experiment design was the same as the first experiment.The results were shown as follow:1.There were no significant difference in body weight,DMI,ADG and F/G all groups of 1~21 d and 22~42 d(P>0.05).There were significantly increased in body weight and ADG among oregano oil addition groups of 43~63 d(P<0.05),but the DMI and feed to gain in groups were no significant difference(P>0.05).The average daily gain and feed conversion ratio of sheep fed corn straw-based diets were significantly higher than that of sheep fed wheat straw-based diets(P<0.05);2.There were no significant differences in the apparent digestibility DM,OM,NDF and ADF between the treatments(P>0.05),but supplementation oregano oil significantly increased the content of nitrogen deposition(P<0.05).The apparent digestibility of OM of sheep fed corn straw-based diets were significantly higher than that of sheep fed wheat straw-based diets(P<0.05);3.The oregano oil supplementation in diets with different straw source had no significant differences on the concentrations of TP,ALB,GLO,ALT,AST,ALP,LDH,UN,TG and CHO(P>0.05).The concentrations of blood glucose of lambs fed supplementation with oregano oil diets were significant higher than others group(P<0.05),and had a tendency to increase the concentrations of ALT(P<0.10).4.The oregano oil supplementation in diets with different straw sources were significantly decreased the ruminal pH and increased the concentration of total VFA,but the concentration of individual fatty acid and the ratio of acetate to propionate were no significant difference(P>0.05).The concentrations of butyrate of lambs fed supplementation with oregano oil diets were significant higher than others groups(P<0.05).Meanwhile,the number of Streptococcus bovis and Butyrivibrio fibrisolvens of lambs fed wheat straw-based diets were significant higher than that of sheep fed corn straw-based diets(P<0.05),and were significantly decreased the number of Selenomonas ruminantium(P<0.05);Adding oregano oil significantly affect the number of Selenomonas ruminantium(P<0.05).The oregano oil supplementation in diets with different straw source significantly increased the content of C18:2 n-6t and C18:3 n-3 in the longissimus dorsi of Hu sheep(P<0.05),but had no effect on the content of saturated fatty acid,unsaturated fatty acid,polyunsaturated fatty acid,monounsaturated fatty acid in each groups(P<0.05).In summary,the enzyme and oregano oil supplementation in diets with corn-based straw and wheat-based straw could effectively improve the growth performance and nutrient digestibility of lambs.Meanwhile,increased the concentration of TVFA in rumen,but had no negative effects on nutritional metabolism.Enzyme and oregano oil could be widely used in ruminant diets,which may provide new theoretical basis for reasonable untilization of crop straw and high-efficient productivity of mutton sheep. |
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