Effect of Split-sex Feeding with Different Protein Levels on Growth Performance, Blood Profile, Pork Quality and Economic Analysis in Growing to Finishing Pigs

Abstract

Split-sex feeding system has been broadly utilized in foreign countries however, it has not worked well for animal industry in Korea. The split-sex feeding means that gilts and barrows are separated and fed their diet with different feeding program. This is based on the finding that gilts and barrows have different growth rates, feed efficiencies and nutrient requirements. So far, the most of feeding study for pigs has designed in the absence of separation of barrows and gilts. Thus, the role of sex in experimental diet impacts on efficiency of feed utilization has not been assessed. A study was conducted to evaluate the effects of split-sex feeding with different protein contents in diet on growth performance, blood profiles, pork quality and economic analysis in pigs from growing to finishing. A total of 160 growing pigs ([Yorkshire × Landrace] × Duroc), averaging 30.55 ± 5.925 kg body weight, were assigned into one of five treatments. Each treatment diet is provided as followed by treatment 1) control (CON): barrows and gilts were penned together with protein requirement of NRC (2012), 2) Gilt: gilts were separately penned with protein requirement of NRC (2012) 3) Barrow : barrows separately penned with protein requirement of NRC (2012) 4) Gilt –1% : gilts were separately penned with 1 % lower protein requirement of NRC (2012) 5) Barrow – 1% : barrows were separately penned with 1 % lower protein requirement of NRC (2012). In feeding trials, the split-sex feeding by NRC requirement had no significant differences on BW, ADG and G:F ratio compared with those of CON treatment (mixed treatment). However, split-sex feeding fed low protein diet had detrimental effects on growth performance. The blood creatinine in gilts was higher than that of barrows at 6 week. The BUN (blood urea nitrogen) concentration was decreased as dietary protein level decreased at 3 and 6 weeks and gilts showed lower BUN concentration than barrows at 9 week. The backfat thickness of barrows showed significantly higher than that of gilts regardless of dietary treatments. Pork color, cooking loss, shear force and proximate analysis of longissimus muscle were not affected by dietary protein, however, barrows showed higher WHC (water holding capacity) than that of gilts. The greatest economical profit was obtained in condition of sex split feeding without lowering CP in the diet. In conclusion, split-sex feeding had no detrimental effects on growth performance and pork quality but economical profit was decreased when pigs were fed low protein diet.