مجله پژوهش در نشخوار کنندگان
سال یکم شماره 2 (تابستان 1392)

This experiment was conducted to evaluate feeding behaviors of lambs regarding to restaurant wastes (RW) usage in the ration. Thirty-six hybrid lambs of three genetic groups randomly allocated into three groups and were kept and fed individually. Dietary barley grain replaced by RW in the levels of 50 and 100 % and along with control group (no RW) was studied. Inclusion of RW in finishing rations of lambs was changed particles distribution in total mixed rations (TMR) in which proportion of long, medium and short particles were increased and fine particles decreased comparing to control group (P<0.05). Selective consumption of TMR was determined at 1 and 8 hours and eating rate was measured at 1, 2, 4 and 8 h after the morning meal. RW usage in the finishing diet of lambs had no effect on total dry matter intake; however it changed selective consumption from different particles of TMR at different hours of feeding. In the diets containing RW, animals tend to sort against long particles and for short and fine particles of the TMR (P<0.05). Also RW usage in the rations has changed eating rate of animals at different hours after feeding (P<0.05). This experiment revealed that finishing lambs, to prevent the change of rumen pH and osmolality, can control rumen health by change of feeding behavior especially eating rate in the next hours after feed delivery.

This study was conducted to investigate the effects of alfalfa particle sizes (long vs. fine) and treating canola meal with hydrochloric acid solution (with purity of 38 percent and level of 5 percent) on physical effectiveness, intake, apparent total tract digestibility of nutrients and feeding behavior in sheep. Four ruminally cannulated sheep fed with TMR. Experimental diets were including: 1) canola meal treated and long alfalfa 2) canola meal treated and fine alfalfa 3) not treated canola meal and long alfalfa 4) not treated canola meal and fine alfalfa. Obtained data from experiment were analyzed by a 4×4 Latin square experimental design. Particle size distribution was determined by dry- sieving procedure and used to partition of feed component and TMR among percentage of long (larger than 19 mm), medium (between 19 and 8 mm) and small (between 8 and 1.18 mm) particles. According to study results, Reduction of particle size increased daily NDF intake (kg) (P<0.05), but decreased the proportion of physically effective NDF (peNDF) in the ingested rations (P<0.05), however canola meal treatment had no effect on them (P>0.05). Reduction of particle size increased DM intake but decreased digestibility of NDF and OM (P<0.05). Treatment of canola meal with hydrochloric acid solution decreased DM intake but increased CP digestibility (P<0.05). Total chewing activity, rumination and eating time reduced when particle size decreased and canola meal was treated (P<0.05). This study showed that reduction of forage particle size was the most effectiveness factor on DMI and chewing behavior (P< 0.05).

The aim of this study was to determine the effect of different levels of G-bind on rumen bacteria activity and protozoa population of Arabi sheep. Experiment was conducted using completely randomized design with twelve Sheep (4 head per each treatment) that fed with diets containing 2 and 4% G-bind, ad libitum for 28 days. Treatments were including a basal diet (control), basal diet with 2% and basal diet with 4% of G-bind. Rumen fluid was taken after 3 hours after the morning feeding by vacuum pump. After staining with logol solution, methylene blue and brilliant green, morphology and protozoa population was counted by hemocytometer lam. Also digestibility of straw for 24, 48 and 96 hours incubation determined with using culture medium of rumen bacteria. The result showed that, protozoa numbers in the treatment containing G-bind were lower, (7.25 × 10-4, and 2.87×10-4 per ml for 2 and 4% respectively) (P<0.05). Species of Holotricha, in the diet containing 4% G-bind had generally omitted. Disappearance of dry matter and natural detergent fiber (NDF) by rumen bacteria at 24 hour incubation was the highest for 4% G-bind (92.26 and 8.60 % respectively). Counting bacteria by MPN method showed that the greatest bacterial population was for 4% G-bind treatment. Therefore, the results suggests that using of 4% G-bind had the appropriate effect on reduction of ciliate protozoa population, increase rumen bacteria populations and NDF digestibility in compared with 2% G-bind.

This experiment was conducted to study the yield performance, chemical compositions, mineral contents and in vitro ruminal fermentation parameters in leaves and stem of Hamedani alfalfa during three consecutive cuttings (harvested at early bloom). Chemical composition and parameters of in vitro gas production of stem and leaves were seperately measured using standard procedures. The lowest crud protein (CP) content of leaves and stem was observed at the second cutting and the highest CP values were recorded at the third cutting (p<0.05). Also, at the second cutting the greatest values of neatural detergent fiber (NDF) was noted in stem, whereas the amount of this parameter for leaves was observed at third cutting(p<0.05). With the increasing number of cuttings the iron, copper and manganese content of stem decreased (P<0.05). The phosphorus content of stem was highest at the second cutting, while zinc had the highest concentration at the first cutting (P<0.05). There was an increment in iron content of leaves due to the numbers of cutting; however other minerals widely fluctuated over cuttings. The lowest organic matter digestibility of stem was observed at the second cutting, and highst value for leaves was seen at the third cutting (P<0.05). At the third cutting the highest value of NDF digestibility and metabolizable energy of leaves were observed, while the recorded value of microbial mass and partitioning factor were maximum at the second cutting. Overall, the result of this study showed that the quality of tested alfalfa was in the order of second cutting>third cutting> first cutting.

The aim of this study was to evaluate the factors affecting days open (DO) as the main reproductive performance and longevity index in Holstein dairy cows in Iran. The demographic, production and reproduction data of six large dairy farms were used. The data were analyzed using Standard Least Squares models. Survival analysis using Kaplan-Meier method was used to determine the impact of DO on longevity. The results showed that DOand dystocia were increased during the recent years (P<0.01). Days open was increased due to the higher milk yield in recent years (P<0.01). Non-eutocia calving also increased the DO (P<0.01). Parity impacted DO and cows in their 6th or more lactations had the highest DO (P<0.01). Male calves increased DO (P<0.05). Sire origin had significant impact on DO and Iranian sires had the lowest DO compare to their counterparts (P<0.01). Season of calving had significant influence on DO and cows calved in winter had higher DO compare with their counterparts calved during summer (P<0.01). Increase in DO during the first calving had a negative impact on cow longevity and cows with more than 160 days of DO were culled sooner (P<0.05). In conclusion, the results of the present study demonstrate that DO as the main reproductive performance index is impacted by genetic and environmental factors.

In this research, milk yield and fat percentage records of Iranian Holstein dairy cattle were used for investigating the existence of genotype by production level interaction via multi-trait random regression model. The records of first lactation were extracted from the database of National Animal Breeding Centerfor cows calved between 2001 and 2010. Herd-years of calving were grouped in low, medium and high production levels based on milk yield and fat percentage. For milk yield, 827295 records from 98136 cows/2146 herds and for fat percentage, 713053 records from 87928 cows/2395 herds remained in the data file. (Co)variance components for milk production traits were estimated by restricted maximum likelihood (REML) method. For milk yield, rank correlations of estimated breeding values for 305-d yield between low and medium production levels and between low and high production levels were 0.77 and 0.78, respectively and for fat percentage, among all levels were higher than 0.90. Genetic correlations between low and high production levels and between low and medium production levels of milk yield in early and late lactation period were less than 0.8; but correlation between medium and high production levels of milk production and between all levels of fat percentage were high. Re-ranking of sires in different production levels led to ratings and genetic correlations lower than 0.8 implying to significant presence between genotype and environment interaction.

The object of this study was to estimate (co)variance components and genetic and environmental parameters for body weights at different ages in Lori-Bakhtiari sheep using a Bayesian approach.In this study, pedigree information and birth weight, one month weight, weaning weight, 6 month weight, 9 months weight and 12 months weight, of 7697 lambs from the 291 rams and 2097 ewes were used. The data was collected in Shahrekord sheep breeding station (sholi) during 1989- 2011. The SAS statistical software was used to determine the effect of environmental factors, and MTGSAM software via Gibbs sampling was applied to estimate genetic parameters. Environmental factors like birth year, sex, type of birth and age of mother on lambing timehad significant effect on traits, which included in the model as fix effects. Animal’s age at weighting day was introduced to the model as covariate. Using best chosen model, the direct heritability for birth weight, one-month, weaning weight, 6 months weight, 9 months weight and 12 months weight were respectively obtained as follows: 0.33±0.03, 0.11±0.02, 0.15±0.02, 0.23±0.02, 0.29±0.03 and 0.38±0.03. Gibbs sampling in Bayesian statistical analysis could provide reasonable range expected estimations for parameters. The results showed that growth traits more are influenced by mother’s genetic factors in the early of age. With increasing age, due to decreases dependence to her mother, the significance of this effect is reduced. The lower to moderate estimates of direct heritabilityfor growth at different ages, obtained in this survey indicate that selection for these traits will be lead to lower to moderate genetic improvement.