Study On Production Performance, Body Composition Traits, Digestion Metabolism In Sheep

With the implementation of the national ecological protection strategy, the space for grazing is becoming less and less, the proportion of confinednessis growing, therefore it became more and more important for scientific researchers to improve the benefits. Feed costs account for 65%~70% of the total cost. So currently,how toimprove the feed efficiency and decrease the feed consumption is one of the most important problems in sheep industry. This study examined 137 male Hu lambs at age of 115 d to 165 d, individual BW(Body weight, BW) and DMI(Dry matter intake, DMI) were measured, calculated the ADG(average daily gain, ADG), FCR(Feed conversion rate, FCR) and RFI(Residual feed intake, RFI), meanwhile, correlation among characters were analyzed, growth traits, slaughtering performance, body composition and blood metabolic variablesanalysis of variance to search the major factors influencing the sheep RFI. Through the research on the activities and expression of coding genes about energy metabolism related enzyme, to explore there gulative mechanism of feed conversion efficiency and the methods to improve feed utilization rate of sheep. Our results showed that:1. Total of 137 Hu sheep with initial BW(BW0, 115d) and final BW(BW50,165d) are 24.72±3.95 kg and 37.26±4.56 kg, DMI, ADG, FCR and RFI are 1.22±0.18 kg/d, 0.252 kg/d, 4.90±0.59 and 0.00±0.09 respectively.2. According the criterion of RFI±0.5SD, the animals were classified as high RFI(greater than mean plus 0.5 SD; 41 males), medium RFI(±0.5 SD of the mean; 52 males), and low RFI(less than mean minus 0.5 SD; 42 males). Based on the analysis of variance between feed efficiency index and growth characteristics of different RFI sheeps, found that DMI, FCR and RFI exist significant differences between different RFI sheep groups(P<0.01), of which the DMI, FCR and RFI are lowest in Low-RFI group, and then significantly lower than High-RFI and Medium-RFI groups, while the ADG, MBW(Metabolic BW, MBW) and relative growth rate have no significant difference among three groups(P>0.05). The correlation analysis showed that the RFI was significantly and positively correlated with the DMI(r=0.514) and FCR(r=0.618)(P<0.001), there were no significant correlations between RFI and BW0, BW50, ADG or MBW(P>0.05).3. High-RFI group sheeps had a significantly lower rumen p H than that of Low-RFI group sheeps(P<0.05), and a higher propionate proportion(P<0.05). There is no significant difference except ADF apparent digestibility between EHigh-RFI and ELow-RFI groups, which higher in ELow-RFI group sheeps compared EHigh-RFI group(P<0.05).4. By analysis slaughter performance, the results showed that slaughter traits have no difference among three groups(P>0.05). The correlation analysis showed that significant correlations were only estimated between RFI and Eye muscle area(r=0.188). Sheeps in High-RFI group have a significantly reduce in cooking percentage and b* value, while pressure loss rised compared to Low-RFI group(P<0.05).5. Through the variance analysis of weight of organs and length of intestinal tract, weproved that weight of liver, lung, testicles, and total of weight stomoch and intestinal tract(P<0.05 or P<0.01).Weight of liver, total of weight stomoch and intestinal tract in Low-RFI group were found to be significantly less than Medium-RFI group(P<0.01). The weight of rumen in Low-RFI group sheeps is significantly lower than Medium and High-RFI groups(P<0.01), but the weight of abomasum is significantly lower than Medium-RFI group(P<0.05), there was no difference with High-RFI group(P>0.05).Weight of jejunumand colon in Low-RFI group are significantly lower than Medium-RFI group(P<0.05), no significant difference in others(P>0.05). Absolute and relative lengthof duodenal in Low-RFI group is highly significantly longer than that in Medium and High-RFI groups(P<0.01), absolute and relative length of ileum is longer than High-RFI(P<0.05), absolute length of cecum is significantly shorter than Medium-RFI group(P<0.05). Total length of intestinal has no difference among 3 groups(P>0.05).6. Sorted by residual feed intake, selected 15 RFI extrem high(EHigh-RFI) and extrem low(Elow-RFI) sheeps respectivly. Serum LDH activity and thyroid hormone, adrenocorticotropic hormone concentration are significantly decreased in ELow-RFI sheeps(P<0.01).7. Expression of LDH gene in muscle and liver tissues significantly increased in Low-RFI group(P<0.01),the expression CS gene in liver is significantly decreased compared with EHigh-RFI sheep(P<0.01), while the expression in muscle have no difference(P>0.05).