Influence of feeding varying crude protein and digestible energy levels on the development of individual muscles, rate of lean and fat deposition in pigs reared from 9 to 60kg liveweight in a humid tropical environment
Four crude protein levels (18,21,24, and 27%) and four digestible energy levels 3,000; 3,300; 3,600 and 3,900) were formulated to investigate their respective influences and interactions on the development of ten major muscles regarded as prime cuts and efficiency of lean deposition in pigs fed from 9 to 60kg liveweight.
Neither energy nor protein levels significantly influenced the relative weights of the ten muscles. Significant energy and protein interactions were observed in the development of Biceps femoris and Psoas major muscles, when expressed as percent of weight. When expressed as percent of total dissectible lean, Biceps femoris and Longissimus dorsi muscles were influenced significantly by protein and energy levels. Maximum weight of Biceps femoris occurred on the 24% protein level and 3,000 kcal DE/kg energy level but the value was not significantly superior to that obtained on the 27% protein and 3,600 kcal DE/kg levels. Relative maximum weight of Longissimus dorsi was obtained on the 27% protein and 3,600 kcal DE/kg energy levels. Dietary protein and energy levels significantly influenced rate of lean tissue deposition and sex x protein interactions were also observed. Castrated males had the greatest rate of lean tissue deposition at 21% protein diet, while the maximum rate was observed in the 24% protein diet in the females. Efficiency of feed utilization for lean deposition was influenced by both protein and energy only in the female pigs. Daily rate of fat deposition was influenced by protein and energy levels and a pronounced sex to protein interaction was observed. In the castrated males, increasing protein level (24 to 27%) resulted in decrease in the rate of fat deposition. In females and pooled data, rate of fat deposition was lowest on the 27% protein level.
Keywords: muscles, rate, development, lean,efficiency