Study On Influence Of Growing-phase Nutrition On Growth Developing, Blood Hormone, Digestibility Regularity And Fattening Performance Of Wannan Cattle

A series of eight experiments were conducted to study the influences of growing-phase nutrition on growth performance, blood hormone, digestibility regularity and fattening performance of wannan cattle and causal relationship between each other, to provide the theoretic data and technical reference for indigenous cattle breeds during meat production. Thirty castrated Wannan cattle of6-month-old and similar weights were randomly and equally divided into five groups that were provided a feed concentrate at1.9%,1.6%,1.3%,1.0%and0.7%of their body weight for twenty-four months, the fattening-period was three months and the feeding program was same.The results of influence of nutrition on growth performance showed that nutrition didn’t affect the body weight, heart girth, body height and length (P>0.05). The results of influence of nutrition on blood hormone showed that nutrition didn’t affect the growth hormone, insulin, thyroid-3, thyroid-4and testosterone content(P>0.05). Age and season significantly affected blood hormone(P<0.05), growth hormone(GH), insulin(INS), thyroid-3(T3) and thyroid-4(T4) content decreased with age increasing, but testosterone(T) content increased with sex maturation. The five kinds of hormone content all decreased with temperature improving, and high-concentrate groups decreased significantly (P<0.01).The results of the effect of growing-phase concentrate dosage on roughage intake and apparent digestibility of nutrients showed that there was trendency to reduce as concentrate proportion decreased for the apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE) and general energy (GE). There was trendency to increase first and then reduce as concentrate proportion decreased for the apparent digestibility of NDF and ADF, the apparent digestibility of NDF and ADF of G1.0group was highest.The results of effect of growing-phase nutrition on apparent digestibility of nutrients of fattening-period animal showed that there was trendency to increase first and then decrease with growing-phase concentrate dosage decreased.for the apparent digestibility of dietary nutrients.The results of effect of growing-phase nutrition on slaughter performance and beef quality on fattening cattle showed that the growing-phase nutrition of G1.0group was most conducive to fat deposition and distribution and increased significantly the proportions of high quality beef (P<0.05). The higher content of fat and higher quality index the longissimus dorsi muscle(LM) of G1.0group suggested that Wannan cattle had the potential of producing marbling even snowflake beef according to the national standard of beef grading.