Protein Requirement For Guanzhong Dairy Lambs At The Age Of 1～90 Days

Guanzhong dairy lambs at the age of 1~90d were used as experimental animals to measure protein apparent digestibility of milk and other three kinds of feeds for Guanzhong dairy lambs at different ages. At the same time, a factorial method was used to research requirements of crude protein, digestible crude protein of lambs at the age of 1~90d and 10 kinds of essential amino acids at the age of 1~30d. And then, on the basis of all above, we used computer simulation method to research proper protein levels of lambs'supplementary in order to supply basic research data to establish systemic feeding standards of Guanzhong dairy goat and formulate scientific artificial feeding program of lambs.1. Protein apparent digestibility of fresh milk and other three kinds of feeds for Guanzhong dairy lambs at different ages16 Guanzhong dairy lambs with close birthdays were divided into 4 groups randomly. Every group has 4 lambs and each lamb was taken as 1 repeat. We adopted total feces collection method to do digestibility and metabolic experiments. 4 groups were used to measure dry matter and crude protein apparent digestibility of fresh milk, supplementary, green hay, corn silage at different ages, respectively. The results showed that:(1) Along with age increased, dry matter and protein apparent digestibility of milk for lambs descend slowly at first, and then rise a little, at last descend quickly. The protein digestibility of milk is 95.20±0.32%, 91.31±3.18%, 93.13±2.40% and 86.05±4.36% for lambs at the age of 9~12d, 22~25d, 45~47d and 75~77d, respectively. But dry matter and protein apparent digestibility of supplementary, green hay and corn silage rise gradually. Protein digestibility of supplementary is 67.34±2.88%, 69.93±7.65% and 73.53±5.61% for lambs at the age of 22~25d, 45~47 and 75~77d, respectively. Protein digestibility of green hay and corn silage is 38.90±9.33%, 51.06±12.06% and 40.03±5.74%, 62.79±10.88% for lambs at the age of 45~47d, 75~77d, respectively.(2) Digestibility of milk, supplementary, green hay and corn silage for lambs at the age of 1~90d has large differences. Dry matter and protein digestibility for lambs at this stage were all shown as milk > supplementary > corn silage > green hay.2. Protein requirement for Guanzhong dairy lambs at the age of 1~90 days64 one day-old Guanzhong dairy lambs with close birthday and close weight were chosen as the experimental animals (half male and half female).According to factorial method to research protein requirements of crude protein, digestible crude protein for lambs at the age of 1~90d and 10 kinds of essential amino acids at the age of 1~30d. The results showed below:(1)Regression equations were established on the requirements of crude protein, digestible crude protein for lambs at the age of 1~90d and 10 kinds of essential amino acids (Lysine, Arginine, Histidine, Isoleucine, Leucine, Methionine+Cystine, Phenylalanine, Tyrosine, Threonine, Valine) at the age of 1~30d(2)According to the regression equations, requirements of crude protein, digestible crude protein and 10 kinds of amino acids were recommended under different body weight and different daily gains.3. Research of proper protein levels in supplementary for lambs at the age of 31~90d28 one day-old lambs with close birthday, close weight and healthy body were chosen as experimental animals (male). Change regularity of body weight and daily gains were researched under artificial feeding program as well as intake regularity. According to the results of protein requirement for Guanzhong dairy lambs at the age of 1~90d, we adopted computer simulation method to calculate the proper protein levels of lambs'supplementary. Results showed: Protein level of supplementary is front-low-rear-high for Guanzhong dairy lambs at the age of 31~90d. The proper levels are 16~17% and 18.5% for lambs at the age of 31~70d and 71~90d, respectively.