Effect of a moderate feed restriction on subsequent growth and body composition in pigs raised under high environmental temperatures

摘要

The experiment was conducted to assess the influence of a moderate feed restriction during the growth period on overall performance, corporal traits and fatty acid composition in pig backfat in pigs raised under high environmetal temperatures. A hundred Large White x (Large White x Landrace) barrows with an average initial weight of 34.5 kg were randomly distributed, in pens (10 pigs per pen). Fifty pigs were fed ad libitum for 36 days (AL pigs) and another fifty were restricted by 25% of their ad libitum consumption during the same period (R pigs). During the subsequent re-feeding period (64 days) all pigs were fed ad libitum. The only diet used contained 13.4 MJ ME kg~(-1), 17% crude protein and 1.3% lysine. The minimum, maximum and mean average temperatures recorded during the feed restriction and post-restriction periods were, °C: 21.5 ±1.2, 28.6 ±1.3 and 25.0±1.1, and 22.6±0.9, 31.2±1.0 and 26.9±0.9, respectively. Considering the whole study period, the average daily gain and average daily feed intake were higher (P<0.05) for AL pigs than for R pigs (840 vs 808 g and 2478 vs 2383 g), although the feed conversion ratio was not different (P>0.05) (2.95 vs 2.95 kg kg~(-1)). At the end of experiment, no differences for dorsal fat thicknessand area and for longissimus dorsi muscle depth, width and area, measured at site of the last rib by means of a real-time ultrasound device, were found between experimental groups. The linolenic acid proportions of the subcutaneous fat outer and inner layer were higher in AL than in R pigs (P<0.05), while palmitic and saturated fatty acids total proportions of the subcutaneous fat inner layer were higher in R than in AL pigs (P<0.05).