Studies On Nutrition Metabolism And Fattening Technique Of Two Chinese Peripheral Blood Hybridization Yellow Cattle

The experiment was carried out to evaluate the rumen fermentation^nutrients apparent digestibility> blood biochemical constituents, growth performance, carcass characteristics and meat quality of Chinese peripheral blood hybridization yellow cattle based on variations in nutrition levels and sex.In experiment one, the research was carried out to evaluate the effects of two dietary energy levels (TDN:70%,76%DM) and two protein levels (1)11.9%CP,7.7%RDP,(2)14.3%CP,9.4%RDP on rumen fermentation, nutrients apparent digestibility, blood biochemical constituents of Chinese crossbred yellow cattle. Four ruminally fistulated Charolais×Nan yang yellow bulls, about570±23kg live weight, were randomly assigned according to a2×2factorial arrangement in a4×4latin square design to receive four dietary treatments. The treatments were as follows:low energy and high protein LEHP(TDN:70%,CP:14.3%, RDP:9.4%), high energy and high protein HEHP (TDN:76%, CP:14.3%, RDP:9.4%), low energy and low protein LELP (TDN:70%, CP:11.9%, RDP:7.7%), high energy and low protein (TDN:76%, CP:11.9%, RDP:7.7%). Each experimental period consisted of16d which provided13d for dietary treatments adaption and3d for sample collection. During the sample collection period, ruminal contents were sampled at0,2,4,6,8,10and12h after feeding to determine ruminal pH, the concentrations of VFA, and ammonia N, Urine and fecal were total collected each day, blood samples was collected from the jugular vein into tubes containing12mg of EDTA at0,6,12h after the morning feeding on the final day.The result revealed that ruminal pH and total volatile fatty acids (VFA) were not affected in all treatments. Acetate concentration was lower and propionate concentration was greater (P<0.01) for bulls fed HE compared with the LE diet. Higher ammonia nitrogen (NH3-N) concentration was in bulls fed HP diet as compared to bulls fed LP diet (P<0.01). Total apparent digestibility of dry matter (DM), crude protein (CP), organic matter (OM) and N utilization were greater for bulls fed HE vs LE diet (P<0.05), but digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were not influenced by the dietary treatments(P>0.05). Bulls fed HP diet had increased N retention than LP diet (P<0.05). The total protein, glucose, triglyceride concentration of blood plasma were similar among all dietary treatments(P>0.05).Plasma urea nitrogen(PUN) was greater in HP dietary treatment (P<0.05)In experiment two, the research was carried out to evaluate the growth performance, carcass characteristics and meat quality of FI Angus×Chinese Xiangxi yellow cattle based on variations in nutrition ievels and sex. Forty-seven Xiangzhong black cattle (Fi Angus×Chinese Xiangxi yeiiow cattle were selected, steers, n=23; heifers, n=24) and fed the same ration during the backgrounding period for i84days. The animais were put in a2×2×2factorial arrangement to determine the effects of2 levels of dietary energy (TDN:70%,80%DM) and protein(CP:11.9%,14.3%DM) and sex(S:male, female) during the finishing phase for146days until slaughter. The treatments were as follows (1) high energy and low protein (HELP; TDN:80%DM, CP:11.9%DM),(2) high energy and high protein (HEHP; TDN:80%DM, CP:14.3%DM),(3) low energy and low protein (LELP;TDN:70%DM, CP:11.9%DM) and (4) low energy and high protein (LEHP; TDN:70%DM, CP:14.3%DM). Six steers and six heifers were located in each treatment, excluding HELP, which contained five steers and six heifers.The result revealed that the growth rate and final carcass weight were not affected by the dietary energy and protein levels or sex. Compared with cattle fed an LE diet, cattle fed an HE diet had lower dry matter intake (DMI,6.76vs7.48kg DM/d, P<0.01), greater chest girth increments (46.1vs36.8cm, P<0.01), and higher carcass fat (19.9vs16.3%, P<0.05) and intramuscular fat content (29.9vs22.8%DM, P<0.01); in addition, the cattle fed an HE diet had improved top and medium top grade commercial meat cut yield (39.9vs36.5%, P<0.05). The dressing percentage was higher for cattle fed an HP diet than an LP diet.(53.4vs54.9%,P<0.05). Steers had a greater length increment (9.0vs8.3cm, P<0.01). but lower carcass fat content (16.8%vs19.4%) than heifers. The meat quality traits including shear force value, drip loss, cooking loss and water holding capacity were not different among treatments or sex and averaged3.14kg,2.5%,31.5%and52.9%, respectively, and the nutritive profiles (both fatty and amino acid composition) were not influenced by the energy or protein levels or sex.Results from the two trails indicated that energy level played an important role on dietary nutrients assimilation. Higher dietary energy and protein concentrations minimize N excretion without having negative effect on animal health for Charolaisx Nan yang yellow bulls. And for Angus x Chinese Xiangxi yellow cattle(Fl), high energy level of the diet increased the fat composition of the carcass and iongissimus muscle between the i2th and13th ribs.High protein ievel of the diet increased the dressing percentage. Steers had less fat deposition ability than heifers.