مجله علوم دامی ایران
سال چهل و یکم شماره 4 (زمستان 1389)

This experiment was conducted to determine the effect of feeding Soybean Oil (SO) along with vitamin E on performance and mammary gland health in Holstein cows. Eight Holstein lactating cows were employed in a 2×2 factorial experiment and in an incomplete replicated latin square design. Treatment diets were: 1) 0% SO plus 0 IU of vitamin E, 2) 3% SO plus 0 IU of vitamin E, 3) 0% SO plus 8000 IU of vitamin E, and 4) 3% SO plus 8000 IU of vitamin E. At the end of each period milk and blood samples were taken. Increasing dietary vitamin E increased milk fat. Soybean oil addition decreased milk fat production, and increased milk lactose. Neither soybean oil nor the interaction of SO by vitamin E had any effect on either milk Somatic Cell Count (SCC) or Total Microbial Count (TMC). Animals fed Vitamin E had lower SCC and TMC than animals not fed the vitamin. Results finally indicated that vitamin E supplementation at a high level reduces SCC while increasing mammary gland's health in lactating dairy cows.

Three experiments were conducted to study the chemical composition and the effect of variety, cultivation area as well as enzyme supplementation on the apparent and true metabolisable energy of triticale. In the first experiment, the precision-fed rooster assay was employed to determine the true metabolisable energy corrected for nitrogen in triticale. In the second and third experiments, Total Excreta Collection method, using male broiler chicks (20-23 days of age), was employed to determine the apparent metabolisable energy corrected for nitrogen in triticale with/without exogenous enzyme supplementation. The chemical composition of triticale was recorded as: EE, 1.65±0.29; CP, 14.00±1.37; CF, 4.92±0.49; Ash, 1.77±0.33; NFE, 77.6±1.62% and CE, 4180±95 kcal/kg. A wide variation in CP (12.2 to 17% on a dry matter basis) and NFE (74.7 to 79.8% on dry matter basis) was recorded among triticale samples. The average true and apparent metabolisable energy corrected for nitrogen in triticale and on a dry matter basis, were 3380±112 and 3244±82 kcal/kg, respectively. The results indicated that the metabolisable energy in triticale was mainly influenced by the factor of cultivated areas. The addition of exogenous enzyme supplementation; xylanase&? -glucanase as well as phytase improved the apparent metabolisable energy in triticale by 155 and 86 kcal/ kg, respectively.

Genetic analysis of growth traits including body weight recorded at birth (bwt), 3 (3bwt), 6 (6bwt), 9 (9bwt) and 12 (12bwt) months of age was carried out using 4107 records on Raieni Cashmere goats born from 206 sires and 1402 dams, during years 1992 to 2006. The records were collected from a resource flock in Baft Research Station, situated in Kerman Province, Iran. The importance of additional random effects including maternal genetic effects, maternal permanent environmental effects as well as direct-maternal genetic covariance on genetic analyses of the growth traits were studied using univariate animal models. Significant maternal genetic effects were found for bwt, 3bwt, 6bwt and 9bwt. Estimates of heritability were upwardly biased when maternal effects ignored. The maternal heritability estimates for bwt, 3bwt, 6bwt and 9bwt were 0.17, 0.09, 0.08 and 0.08, respectively. The maternal permanent environmental effects were pronounced only for 12bwt. The (co)variance components were estimated using a multivariate animal model. Yearling weight was excluded from the model because of its limited number of records. Accordingly direct heritability of bwt, 3bwt, 6bwt and 9bwt were estimated to be 0.26±0.05, 0.30±0.04, 0.33±0.05 and 0.30±0.05, respectively. The genetic correlations among the body weights were high and positive (0.66 to 0.96), which is promising. The respective genetic correlation between 3bwt and the later ages were 0.95 and 0.92. Accordingly, the body weight observed at at weaning age could be employed as a selection criterion for BW genetic improvement in Raieni Cashmere Goat.

This study was conducted to evaluate the effects of alfalfa hay (AH) particle size and soybean hull (SH) on physical effective fibre (peNDF), particle size distribution in diets, chewing activity as well as milk composition and production in early lactating dairy cows. Eight lactating Holstein cows averaging 590±33 kg of BW and 47±13 days in milk were assigned in a 4×4 Latin Square design to a 2×2 factorial arrangement of the treatments: alfalfa hay particle size (fine vs. coarse) combined with soy hull (zero or as a substitute for 50% of AH). The peNDF and physically effective factor (pef) values of diets increased by increase in AH particle size and inclusion of SH in diets (P<0.01). Intake of peNDF was increased by increase in the Particle Size (PS) of AH (P=0.08) and SH inclusion (P<0.01) in diets. Milk production was increased by feeding diets containing SH (P=0.04). Milk fat content was increased by increasing PS of AH (P=0.03) and by decrease in SH substitution (P<0.01). Cows fed coarse AH tended to spend more time chewing in comparison with cows fed fine AH (P=0.08). Coarse particles of AH increased total chewing activity based on min/kg of DMI (P<0.05) and tended to increase the eating activity (P=0.09). When chewing activity was expressed as based on NDF intake, ruminating time and total chewing time tended to be increased by coarse AH being fed (P<0.1). Interestingly when chewing activity was reported as based on peNDF intake, the SH inclusion in diet significantly decreased the eating time (P=0.02), total chewing time (P=0.03) and tended to decrease the ruminating time (P=0.08). SH inclusion in the diets increased pH of the feces (P<0.01). With regard to ruminating time and milk fat percentage, the results of the study indicated that fiber in SH can not be physically as effective as that in AH. In diets containing non-forage fiber sources (as SH in this study) using Penn Stat Particles Separator cannot be a reliable tool for an evaluation of some physical properties of diets.

Thriteen thousand, seven hundred and fifty two (13752) records on growth tarits (birth weight, 1, 3, 6, 9 and 12 month weights) as well as pelt scores, collected during 1996-2002 as Karakul Sheep Breeding Station, Sarakhs, Iran were employed in this study. Best Liner Unbiased Prediction (BLUP) of breeding values, genetic and phenotypic trends of the traits were estimated as the regression of average predicted breeding values and phenotypic values over birth year, respectively. Environmental trends were assessed as the difference between phenotypic and genetic trends. Estimates of genetic trends were found as: 0.013±0.001, 0.034±0.004, 0.119±0.010, 0.087±0.013, 0.127±0.018, 0.119±0.019 kg/year and 0.257±0.019 score/year, respectively. Phenotypic trend for the above traits were -0.151±0.005, -0.116±0.023, 0.268±0.035, 0.185±0.052, 0.443±0.065, 0.559±0.078 kg/year and -0.235±0.048 score/year, respectively. Environmental trend for the same traits were respectively estimated as -0.164±0.004, -0.151±0.019, 0.149±0.025, 0.098±0.039, 0.316±0.047, 0.440±0.059 kg/year, and -0.492±0.029 score/year.

Information on animal daily forage needs is essential for an estimation of rangeland grazing capacity. Accordingly, weight and Animal Unit Equivalent (AUE) for each individual class of animal should be determined. Live weights of Baloochi sheep as based on average live weights of 3 and 4 year old ewes were determined. Five herds of Baloochi breed sheep were selected for the task. In each herd, 15 heads of three year old ewes, 15 four year old ones, 5 heads of three year old rams, 5 four year old ones, 15 heads of three and 15 six month old lambs selected. They were weighted three times namely: once at the beginning of the experiment, once at the end of the grazing season on lowland rangelands, and the third time after being grazed on crop residue of either fields or orchards. Weights of Baloochi sheep (i.e. three and four year old ewes), ram, three and six month old lambs were 41±0.53, 89.18±1.78, 20.15±0.38 and 38.65±0.39 Kg. Accordingly, Animal Unit Equivalent figures (AUE) for ram, ewe, three and six month old lambs were 0.86, 1.54, 0.51 and 0.82 respectively. According to MAFF equation,1984; daily metabolism energy requirement for ewe, ram, three and six month old lambs of Baloochi sheep for maintenance and by considering the standings of rangelands as well as distances from watering points and plant density were obtained as 8.19, 14.66, 6.31 and 10.15 Mj (after being multiplied by 1.3). Dry matter requirement for ewe, ram, three and six month old lambs of Baloochi sheep as based on the forage quality at the vegetative stage was calculated as 1.1, 2, 0.8 and 1.4 Kg and based upon forage quality at flowering stage it was1.2, 2.2, 0.9 and 1.5 Kg. This indicates that the time of grazing affects the on daily forage needs and it is necessary to determine the animal requirement as based on forage quality.

Influence of maternal and sire-generation interaction effects on day-old chick' weight was investigated in two commercial broiler sire and dam lines, and in Mazandaran native fowls. The data were analysed through Restricted Maximum Likelihood (REML) procedures, using ASREML software. Ten different animal models were implemented and compared with likelihood ratio test. All models consisted of direct additive genetic effect but differed in combinations of maternal additive genetic, maternal environmental, sire-generation interaction and covariance between direct and maternal additive genetic effects. In spite of differences in the estimated genetic parameters from different models, the pattern of variations among the three strains was similar. In all strains, fitting direct additive genetic effects without considering other random effects resulted in overestimation of direct heritability (ranging from 0.422 to 0.754). The reduction in these estimates was substantially due to maternal effects, especially direct maternal additive genetic, which accounted for from 15.9% to 62.7% of phenotypic variations, either with or without inclusion of sire-generation interaction. Also, improvement in correlation between direct and maternal additive genetic effects (from -0.100 to 0.12, -0.13 to -0.06, and -0.21 to -0.16, for sire line, dam line and native fowls, respectively), due to the fitting of sire-generation interaction, indicated that its negative estimate is due to the implementation of an inappropriate statistical model.

In the present research, divergent selection for Japanese quail body weight at four and five weeks of age was performed in five generations to estimate the response to selection and realized heritability. The average body weight was significantly (p<0.01) different among lines selected for increasing (HW) vs. decreasing (LW) weight. Cumulative responses to selection for four and five weeks of age body weight during five generations for males and females were respectively 21.15, 18.98 and 18.662, 15.65 in HW line while -22.14, -28.152 and -22.33, -29.47 grams for LW line. The value of realized heritability of body weight for females was higher than that for males in all the lines, with its value decreasing with increase in the age of birds. Selected lines for decreasing body weight showed a higher heritability than the lines selected for increasing body weight. Differences between male and female were significant in all the generations except in generation four. Body weight average varied between the selected and control lines for all the generations.

Genetic and phenotypic parameters related to production traits, udder conformation and somatic cell count for the Iranian Holstein cows were estimated. Monthly records of somatic cell counts (SCC) were primarily transformed into somatic cell scores (SCS) and the the average level of lactation period, with correction for milk volume, was calculated. By use of these estimates an udder health index for Iranian Holstein cows was proposed which consisted of LSCS, fore teat placement as well as udder depth. This index indicates that selection for lower values of LSCS, lower udder depth and closer teats should result in increased mastitis resistance. At the end, a restricted selection index method was employed to compare different selection strategies and to obtain proper weight for mastitis in the breeding goal. Through the definition of the different breeding goals, the simultaneous genetic progress for milk yield as well as the resistance to mastitis were explored. It was finally revealed that with selection for milk yield only, susceptibility to mastitis will increase. But by inclusion of mastitis phenomenon in the breeding program, it would be possible (in the meantime that a continuation of increase in annual milk production is planned) to stop the increase in the trend of mastitis spread.

Effects of Condensed Tannins (CT) on crude protein availability in sainfoin hay was investigated according to most popular ruminant feeding systems. Different treatments including Polyethylene Glycol (6000 MW), sodium hydroxide, sodium bicarbonate, potassium permanganate, wood ash, water and urea, were applied for deactivation of CT Crude protein fractioning was determined using nylon bag technique, AFRC and CNCPS systems. Total phenolic compounds, total tannin and condensed tannin content of control hay were 39.4, 38.5 and 21.3 g/kg DM, respectively. PEG and water treatments resulted in higher CT deactivation values as compared with other treatments. Ruminal crude protein degradability, effective degradability and metabolizable protein content, in sainfoin hay, significantly increased with tannin deactivation. Condensed tannin deactivation, caused the reduction of C fraction in CNCPS while increasing crude protein availability. It can be concluded that deactivation of condensed tannins could lead to an increase in crude protein availability in sainfoin hay. Nonetheless PEG, water and wood ash are the most effective in increasing nitrogen availability. No chemicals are employed in water treatment, it benefits from economic justification and ease of use, and is finally concluded as a low cost practical procedure for the processing of sainfoin on the farm.