Optimal Nutritional Levels for New America-Line Landrace Pigs during Fattening Period

[ Objective] To investigate the effects of different nutritional levels on production performance, apparent digestibility of nutrients and car- cass quality, and determine the optimal levels of energy, crude protein, calcium and phosphorus in diet for the Landrace pigs at fattening stage. [ Method] A total of 36 healthy Landrace pigs at the same parity with close weaning age and similar body weight [ （70 ± 1 ） kg ~ were selected. They were divided into nine experimental groups randomly. The experiment was carried out according to the L9 （3^4） orthogonal design. Then the production performance, apparent digestibility of nutrients and carcass quality were determined, respectively. The preliminary trial lasted for 7 d, and the trial lasted for 42 d. [ Result] The levels of crude protein and calcium had significant effects on the average daily gain （ P 〈 0.05）, and the energy level had extremely significant effects on the average daily gain （ P 〈 0.01 ）. The levels of energy, crude protein, calcium and phosphorus had effects on the apparent digestibility of nutrients in various degrees. The crude protein level had significant effects on the backfat P2 （P 〈 0.05） ; the energy level had significant effects on the backfat P2 and backfat P1 （P 〈 0.05） ; and the calcium level had significant effects on backfat P2 and lean meat percentage （P 〈 0.05）. [ Condasion] During the fattening period, the requirement of digestible energy, crude protein, calcium and phosphorus for the new America-line Landrace pills was 13.39 MJ/ka. 16.00%. 1.45% and 0.90%. respectively.

Appropriate Metabolic Energy, Crude Protein, Calciumand Available Phosphorus Levels of Diet for BlackMuscovy Duck at 43-91 Days of Age

[Objective] The paper was to study the effects of diet formulation with different nutrition levels on growth and slaughter performance ofblack muscovy duck at the age of 43-91 days. [Method] Totally 288 individuals of 43dayold black muscovy duck were randomly divided intonine treatments, four repeats each treatment and eight ducks each repeat. UsingL9 （34） orthogonal experiment design （four factors and three levels）,three metabolic energy levels （12.32, 12.72, 13.12 MJ/kg）, three crude protein levels （14%, 16%, 18%）, three calcium levels （0.6%, 0.8%, 1.0%）and three available phosphorus levels （0.30%, 0.45%, 0.6%） were designed, and a total of nine feeding groups （C1C9） were designed according todifferent nutritional levels. Through combination of feeding test （49 d） and metabolic test （pretest 4 d and formal test 3 d）, the growth performance,meat performance and apparent nutrient digestibility of ducks were determined. [Result] The ducks in experimental group C2 had the highest average daily gain, the lowest feed gain ratio, the largest body oblique length, chest width, chest depth and tibia length, which had significant or extremely significant differences with other groups （P〈0.05 or P〈0.01）. The slaughter rate, semieviscerated rate, eviscerated rate and meat quality ofducks in C2 group were higher （P〈0.05）. The apparent digestibility of crude protein and dietary metabolic energy in C2 group were 88.68% and63.07%, respectively, both were significantly or extremely significantly higher than the other groups（P〈0.05 or P〈0.01）, while the interaction effectof calcium and phosphorus level on apparent digestibility was not obvious. [Conclusion] Under the experimental conditions, the suitable metabolicenergy, crude protein, calcium, available phosphorus and total phosphorus levels of 43 -91 days old black muscovy ducks were 12.32 MJ/kg,16.10%, 0.92%, 0.45% and 0.68%, respectively.