مجله علوم دامی ایران
سال چهلم شماره 4 (زمستان 1388)

Chemical composition, in vitro digestibility and in situ (dry matter and protein) degradability were measured to assess the nutritive value of Sugar Beet Pulp (SBP) treated with Neuspora sitophila fungi. The obtained data were compared using t test. Dry Matter (DM), Crude Protein (CP), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and ash content for untreated SBP were 90, 9.2, 46.6, 30.0 and 5.6 % of DM, respectively, and they after processed by fungi, were respectively 78, 25.6, 27.2, 25.4 and 6.3% of the DM. Treated SBP contained being a lower content of DM, NDF and ADF, but higher CP (P<0.05) than the untreated SBP. Digestibility coefficients (%) of DM, organic matter and digestible organic matter in the dry matter, were respectively, 65.8, 70.9 and 66.9% for untreated SBP, while 82.4, 89.6 and 83.9% for treated SBP. The differences between digestibility coefficients were, statistically, significant (p<0.05). Metabolisable energy of untreated SBP was 44.1 MJ/Kg DM, which was increased (after being processed), to 55.1 MJ/Kg DM (p<0.05). Effective degradability (g/kg DM) at different k (0.02, 0.05 and 0.08/h) were, respectively, 64.1, 54.5 and 46.3 for untreated SBP, and 66.4, 58.5 and 49.9 for treated SBP. The degradability parameters were improved (P<0.05) in the treated SBP. On the other hand, 'a', 'b' and 'c', and MP, also, increased after SBP being treated with fungi (p<0.05). In conclusion, treating SBP with Neuspora sitophila resulted in improving the concentration of CP, digestibility coefficients as well as protein degradability.

An experiment was conducted to evaluate the feeding value of date pits in broiler chickens. One hundred sixty eight male broiler chicks (Ross 308) from 1 to 42 days of age were used. Experimental design was CRD, in a factorial arrangement of 4 replicates per treatment. The factors included: 3 levels of date pits (10, 20 and 30%) either with or without multi enzyme supplementation. A control diet based on corn and soybean meal was included. All diets were isonitrogenous as well as isoenergetic. Apparent metabolizable energy corrected for zero nitrogen retention and amino acids content of date pits were assessed before formulation of the diets. Cage body weight and feed intake were measured at 10, 28 and 42 days of age. At the end of the experiment, two birds from each cage were selected for either blood plasma samples to be used to measure lipid metabolites and peroxidation parameters. Finally, following over night fasting, birds were slaughtered and carcass characteristics evaluated. Results indicated that live body weight at 10, 28 and 42 days of age, weren’t affected by either the levels of dietary date pits or enzyme addition and neither by the interaction between the two factors (P>0.05). Adding date pits to broiler diet, up to 10% improved feed conversion ratio (FCR) significantly (P<0.05). Increasing the level of date pits to diet, up to 20 and 30% increased FCR about 4.9 and 3.1% respectively (P<0.05). No difference was observed between carcasses’ relative weight of birds fed control vs. dietary treatments (P>0.05). Gizzard percentage in birds fed date pits, was 32% greater than that in the control group (P< 0.01). Feeding date pits decreased blood cholesterol and triglycerides numerically, but this decrease, was not statistically significant. The effect of feeding date pits on blood malondialdehyde and total antioxidant was significant (P< 0.05). Data suggested that including 10% date pits would improve broiler performance. Furthermore adding enzyme to date pits containing diet entails have positive effects.

This experiment was conducted to study the effects of Peptide Nitrogen Source (PNS) infusion on ruminal fermentation pattern, nutrient digestibility, and microbial nitrogen production. Three ruminally cannulated Holstein dairy cows BW=682 kg and DIM=210d were assigned in a 3×3 Latin Square of 21-d periods. The first 14 d’s were considered as adaptation period and the last 7 d as sample collection period. Three levels of sodium caseinate as PNS were used in the experiment (0, 50 and 100gr/d considered as diets 1, 2 and 3 respectively). PNS was infused directly into rumen of the fistulated cows just before the offer of morning diet. Purine derivatives method was ebpolyed for daily microbial nitrogen synthesis estimation. Ruminal Ammonia Nitrogen (NH3-N) and Peptide Nitrogen (Pep-N) concentrations (P<0.01), as well as NH3-N to Pep-N ratio (0.58, 0.70 and 0.82 for diets 1, 2 and 3 respectively) were increased by infusion of PNS (P<0.05). Ruminal Volatile Fatty Acids (VFA) concentration bears a tendency to increase (P=0.07) but not significantly by infusion of casein. Acetate increased linearly (P<0.01) and there were no specific changes observed for propionate and butyrate through treatments. The Branched Chain Volatile Fatty Acids (BCVFAs) (i.e. valerate and isovalerate) increased significantly by PNS infusion. Ruminally PNS infusion had a significant effect on NDF, ADF (P<0.05) and especially hemicellulose (P<0.01) digestibility. Volume of urine was significantly affected significantly (P<0.01) by casein infusion in cannulated cows and urine creatinine, uric acid and allantion concentrations increased by PNS infusion. Daily microbial nitrogen yield estimated from purine derivatives (222.86, 238.75 and 257.51 g/d for diets 1, 2 and 3 respectively) were significantly increased through casein infusion into rumen (P<0.01). Fiber digestibility was improved, acetate and BCVFAs increased and microbial nitrogen yield increased by PNS, but a high level of PNS decreased nitrogen efficiency while increasing nitrogenous excretion and BUN. It could be concluded that ruminal microbes need some of their N requirement as peptide and the optimal fiber digestibility and nitrogen utilization efficiency and microbial nitrogen yield was gained when NH3-N/ Pep-N was 0.70 and lower than this value fiber digestibility and microbial nitrogen synthesis decrease and while higher than this value nitrogen utilization efficiency decreases.

Autoselection is a kind of natural selection, that occurs in reproductive traits by inequality of offspring generation and therefore by virtue of the nature of its genes transmission to next generations. In this study, the effects of autoselection on heritability and selection response in reproductive traits by using univariate stochastic computer simulation in artificial selected and unselected populations were investigated. The results showed that, in autoselection and no artificial selection on litter size, additive genetic mean, phenotypic mean and threshold mean increased. Additive genetic variance and heritability had no changes. In autoselection and artificial selection for threshold phenotype on dams and in autoselection and artificial selection for threshold phenotype on dams and for sires base on their mother’s threshold phenotype, the results showed that in high heritability, observed selection response for per generations was more than last generation because with increasing threshold mean, the distribution of threshold phenotype in dam’s population and autoselection response depends to this distribution. Although, autoselection and artificial selection occurred additive genetic variance and heritability had decreased a little, because artificial selection base on threshold phenotype and autoselection prevent to decrease additive genetic variance. Analysis of threshold phenotypic data by MATVEC with threshold model, showed that estimated heritability was less than real underlying heritability and its estimation depends on real underlying heritability, proportion selected and paths of selection.

The objective of the present study was to estimate the relationship between genetic parameters for 13 linear type traits, and milk yield as well as open day in Holstein cattle of Iran. Three data sets of: 16502 (type traits), 16557 (milk yield) and 11631 (open days) records related to the first calving of the cows, and respectively taken from 1500, 1566, and 2000 herd-year-season groups, were taken into account. SAS software and Proc GLM were employed to fit the model. Genetic parameters were estimated using Restricted Maximum Likelihood along with an animal model and ASREML software. Genetic correlation among type traits and milk production ranged from 0.34 (rear udder width) to -0.31 (udder depth), and among type traits and fertility, it ranged from 0.62 (rear udder width) to -0.37 (udder depth). Most of the genetic correlations between milk production and fertility indicate that more production in cows was accompanied by a lower fertility, while cows with a lower production level benefitted from a more fertility rate.

Data related to Yazd native fowls (obtained during 2000-2008) Yazd native fowls were made use of in the present study. The investigated traits consisted of Body Weight at 8 (BW8) and 12 weeks (BW12), Age at Sexual Maturity (ASM), Egg Number during the first three months of production period (EN) and the mean Egg Weight at 28, 30 and 32 weeks of age (EW). The genetic and phenotypic parameters were assessed through univariate as well as bivariate animal model employing ASREML software. The heritability estimates for BW8, BW12, ASM, EN and EW were 0.32± 0.01, 0.37±0.018, 0.21±0.02, 0.14±0.02 and 0.24±0.02, respectively. The respective genetic correlations of BW8 and BW12 with ASM were -0.21±0.05 and -0.28±0.05. Also, the respective genetic correlations of ASM with EN and EW were -0.95±0.017 and 0.29±0.07. The genetic trends during the 6 generations of selection were estimated using regression coefficients of breeding values on generation. Genetic trends of BW8, BW12, ASM, EN and EW were 9.55 gr, 15.35 gr, -0.03 day, 0.031 egg and 0.037 gr. The results of current study indicate that reducing the age at sexual maturity will would lead to an increase in the number of produced eggs.

Such classical growth models as Gompertz and Richards have been extensively used in broiler studies. This study was conducted to explore if 3 types of Hyperbolastic growth models known as H1 (generalized from logistic growth model), H2 (stand alone) and H3 (generalized from Wei¬¬bull growth model) may be empolyed to illustrate dynamic growth response of broilers and also how effective such models would be as compared with the classical growth models. A set of growth data were provided from 92 male broiler chicks reared from 1 to 56 days. Goodness of fit for individual growth model was determined using R2, MSE, RSD and Bias. The results of the present study indicate that, H3 could give a better fit (R2=0.99993) presumably due to its greater flexibility. In addition, H3 showed a higher accuracy and lower error (MSE= 264, RSD=16, Bias=0.5) than the other models, being followed by WeiBull, Gompertz, Richards H2 and H1 growth models, respectively. In the meantime, Logistic growth model appeared with the lowest accuracy (0.99898) and a highest error (3432). A general evaluation in this study revealed that H3 can be considered as a useful tool to fit broiler growth dataset, with the highest accuracy and a lowest error than the other growth models.