RESUMEN
This experiment was conducted to evaluate the supplemental effects of a novel protease produced from Bacillus subtilis in low crude protein (CP) corn distiller dried grain with solubles (cDDGS) based diets on growth performance, carcass attributes, nutrients digestibility, blood chemistry, and intestinal histomorphometry of broiler chickens. One hundred and sixty, one-day-old chicks were randomly allotted to one of 4 dietary treatments. Each dietary treatment had four replicates, with 10 birds in each replicate. Two basal diets were formulated for both starter (1-21d) and finisher (22-35d) phase; (PC) a corn soybean meal based diet as per standard recommendations of Ross 308; (NC) 5% cDGGS with 5% reduction in CP with concomitant reduction in essential amino acids (EAAs) compared with PC. The negative control diet was further subdivided into 3 parts. One part was without enzyme supplementation, while the other two parts were supplemented with a novel protease (PROT1) and a commercial protease (PROT2), respectively. The same procedure was adopted for finisher diets. A digestibility assay (32-35d) was carried out using acid insoluble ash (AIA), an external digestibility marker. At the end of 35d, ileal digesta were collected from four birds per experimental unit for nutrient digestibility measurement. Tissue samples of duodenum, jejunum, and ileum were collected for villus height, villus width, crypt depth, and crypt width. Body weight gain (BWG) and feed:gain were improved (p<0.05) with protease supplementation. No effect was observed on carcass parameters. However, CP digestibility, apparent digestibility coefficient for nitrogen (ADCn), nitrogen retention (Nret ), and apparent ileal amino acid digestibility (AIAAD) were improved (p<0.05). However, there was no effect on apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen (AMEn), blood glucose, total protein and cholesterol (p>0.05) and intestinal integrity (p>0.05). It was concluded that protease enzyme can improve nitrogen and CP digestibility, resulting in improved amino acids availability in low protein diets.(AU)
Asunto(s)
Animales , Bacillus subtilis , Proteínas , Pollos/metabolismo , Nutrientes , Zea maysRESUMEN
(Co)Variance components and genetic parameters for economic traits in Iranian native fowls were estimated using multivariate animal model analysis with DFREML procedure. The data of four stations of native fowls breeding (Mazandaran: 49536, Esfahan: 23108, West Azarbaijan: 24890 and Fars: 30279) was containing records of cocks and hens collected during period of 1988 to 2006. The recorded traits were Body weight (at 8 weeks or 12 weeks), Age at first egg, egg number at 12 first weeks of production and mean egg weight between 28 to 32 weeks. The most estimated heritabilites, except egg number, were more than 0.20. The highest heritabilites for all traits were related to Fars station, whereas most heritabilites in West Azarbaijan were less than other stations. The heritability for egg number was estimated 0.099+/-0.018 for Esfahan to 0.322+/-0.012 for Fars. The estimated heritabilities of body weight were medium to high and varied from 0.228+/-0.014 for Esfahan to 0.548+/-0.014 for Fars, While, the heritabilities of mean egg weight were high and ranged from 0.223+/-0.021 for West Azarbaijan to 0.638+/-0.013 for Fars. The heritability for age at first egg was estimated 0.270+/-0.021 for Esfahan to 0.520+/-0.014 for Fars. The most estimated genetic correlations, except between Body weight and Egg weight and between age at first egg and egg weight, were negative. The direct genetic correlations between maturity age and egg number were high and negative, ranging from -0.384+/-0.033 to -0.987+/-0.003 for Mazandaran and Fars, respectively.