This study was conducted to evaluate the effects of feed form (mash and crumble-pellet) and feed particle size (fine, medium and coarse) on growth performance, carcass characteristics and digestive tract development of broilers. A total of 1,152 one day-old Ross 308 mixed-sex broilers were used in a factorial arrangement (2 × 3) based on a completely randomized design with six replicates of 32 birds each. Higher average daily gain (ADG) and average daily feed intake (ADFI) were observed (P < 0.01) for birds fed the crumble-pellet diets (CPD) than for those fed the mash diets (MD) during starter, grower and the entire experiment period. From d 1 to 40, birds fed CPD had a higher (P < 0.01) body weight (BW) than those fed MD. Birds fed CPD had a lower (P < 0.01) feed:gain ratio (F:G) during the starter phase than those fed MD. Medium or coarse particle size increased (P < 0.01) ADG and ADFI during the starter phase, but birds fed fine particle size diets had lower (P < 0.01) F:G during the grower phase. In MD, medium and coarse particle sizes resulted in higher (P < 0.05) BW, ADG and ADFI than fine particle size during the whole experiment. In CPD, particle size had no significant effect on growth performance, as indicated by a feed form × particle size interaction (P < 0.05). At 41 days of age, ten birds per treatment were randomly selected and killed for slaughter yields and digestive tract characteristics determination. It was shown that particle size and feed form alone had no significant effect on slaughter yields, so changes was the feed form × particle size interaction. The relative empty weight of the gizzard was greater (P < 0.01) and the relative length of the ileum was longer (P < 0.05) in birds fed MD than in those fed CPD. Overall, CPD improved growth performance during the entire period of the study with effects being less evident during the finisher phase than during the starter and grower phases, and the effect of feed particle size varied depending on feed form.

This study was conducted to evaluate the effects of 3 rearing systems ( FL : flooring litter rearing, MC : multilayer cage rearing, PN : plastic net rearing) with or without supplemental narasin on growth performance, gastrointestine development and health of broilers. A total of 2,400 one-day-old Ross 308 mixed-sex broilers (1:1 ratio of males and females) were used in a completely randomized design utilizing a 3 × 2 factorial arrangement of treatments, with 12 replicates per treatment. Each replicate for FL, MC, and PN consisted of 34 birds per floor pen, 30 birds per cage, and 36 birds per net pen, respectively, ensuring the same stocking density (12 birds/m 2 ) across the 3 systems. Results showed that lower ADG (average daily gain), ADFI (average daily feed intake), and FCR (feed conversation ratio) observed in the MC group than those of the other 2 systems from 1 to 36 d of age ( P < 0.05). Narasin inclusion in the diets decreased ADFI and FCR significantly ( P < 0.05). Multilayer cage and PN rearing systems reduced the relative weight of the gizzard significantly ( P < 0.05). Compared with FL, MC reduced the relative weight of the duodenum, jejunum, and ileum ( P < 0.05). The mRNA expression levels of the ileal IL-1β and IFN-γ in FL were higher than those in PN and MC ( P < 0.05). Narasin decreased the ileal mRNA expression of TNF-α ( P < 0.05). Different rearing systems changed the ileal microflora structure of broilers. The FL system increased the ileal microbial diversity of broilers and the relative abundance of Actinobacteria . Narasin combined with MC increased the relative abundance of Proteobacteria . In conclusion, birds reared in PN had a higher body weight. The MC birds had poorer intestinal development and health condition, higher abundance of Proteobacteria , but better FCR. The FL rearing appeared to be propitious for gastrointestinal development and health. Narasin inclusion in the diets improved FCR and changed the relative abundance Proteobacteria of broilers.

No abstract

The PPARγ2 gene is a key regulator of both proliferation and preadipocyte differentiation in mammals. Herein its genotype and allele frequencies were analyzed using PCR-SSCP in eight pig breeds (N = 416). Two kinds of polymorphisms of the PPARγ2 gene were detected, including a previously reported shift SNP A177G (Met59Val) in exon 1 and a novel silent mutation G876A in exon 5. The results revealed that European pig breeds carry a higher allele A frequency at the A177G locus and a fixed GG genotype at the G876A locus. Allele A at the G876A locus was only found in Jinhua pigs. The association between haplotype (A177G/G876A) and carcass and meat quality traits was analyzed in a Pietrain x Jinhua F2 population (N = 248). The PPARγ2 gene was found to be significantly associated with backfat thickness at the shoulder (p < 0.05), 6–7th ribs (p < 0.01), last rib (p < 0.01), gluteus medius (p <0.05) and ham weight (p < 0.01). Significant effects of different haplotypes on ham weight and backfat thickness at the 6–7th ribs, last rib, and gluteus medius were also observed.