مجله تحقیقات دام و طیور
سال سوم شماره 2 (1393)

In this experiment, blood sample was weekly taken from 20 ewes from 17th week of pregnancy. Parameters such as ß- hydroxybutyrate (BHB), glucose, urea, non-esterified fatty acids (NEFA), triglyceride, cholesterol, ALT and AST were measured. After parturition, based on signs and symptoms, ewes were divided into two groups (healthy and pregnancy toxaemia ewe). For ALT, AST and cholesterol there was no significant difference between two groups. The amount of ß- hydroxybutyrate, glucose, urea, non-esterified fatty acids showed significant difference between the groups (P<0.0001). Urea and triglyceride concentration showed an increase and decrease, respectively in pregnancy toxaemia ewes two weeks prepartum. BHB andNEFA values in pregnancy toxaemia ewes were high at 19-20th week of pregnancy and decline two weeks prepartum. In conclusion, pregnancy toxaemia ewes for one month prepartum and two weeks prepartum had high lipolysis (high blood NEFA value) and gluconeogenesis (high blood urea value), respectively for providing the required energy.

The purpose of this study was to compare the different ways of using enzyme in diet on performance, carcass characteristics, overall mortality and litter moisture in broilers. This experiment was carried out on a of 750 total unsexed broiler chickens of the Ross 308 distributed in six experimental treatments. A completely randomized design with five replicates (25 broiler chicks in each replicate) was utilised. Experimental treatments were 1- control diet based on corn-soybean, without multiple enzyme and five treatments based on wheat-barley and different in ways of using multiple enzyme (2- wheat-barley based diet plus enzyme continues 3- enzyme added every other day 4- enzyme added every two days 5- as 2 but enzyme added up to 42 days of age 6- as 2 but enzyme added up to 35 days of age). All dietary treatments were iso-energetic, containing 2900 kcal/kg. The results indicated that birds fed with treatment 3 had greater weight gain while the best feed conversion ratio was observed in treatment 6 (P<0.05). Likewise, birds which received treatments 1 and 5 had higher litter moisture (P<0.05). There were no significant differences among the treatments in terms of overall mortality and carcass characteristics. Finally, the results indicated that there were no significant differences between treatments 1, 2 and 3 in terms of broiler performance. Given the fact that discontinuous use of enzyme could radically reduce feed costs, this method could also potentially be effective in reduction of costs of imports.

The aim of this study was to estimate (co)variance components and genetic parameters for body weights at different ages of Najdi cow using Gibbs sampling of Bayesian approach. For estimating (co variance components and genetic parameters, the records collected over 21 years (1990-2010) in Najdi cattle breeding station (Shushtar city) was used. The traits were body weights in different age (birth weight, weaning weight, weight at age six months (W6), yearling weight and weight at age 18 months (W18). Environmental factors such as birth year, birth season, sex and age of mother had significant effects on birth and weaning weights (P<0.05). W6, yearling, W18 were significantly influenced by birth year, birth season and sex (P<0.05). The best model obtained for birth weight, weaning weight, and W6 was model 2 in which direct additive genetic effect of animal and maternal permanent environmental effects were taken into account. The best model for yearling and W18 was model 1 in which only direct additive genetic effect of animal was included. Direct heritability for birth weight, weaning weight, W6, yearling weight W18 were 0.45, 0.17, 0.10, 0.18 and 0.13, respectively. Low heritability detected in this study (except the birth weight) is due tohigh environmental variance. Therefore, the possibility of improving these traits through phenotypic selection is low by and the genetic progress achieved will not be high. In conclusion, good management beside improved environment quality can change the performance of the traits.

This study was performed to evaluate the effects of water temperature and adding potassium carbonate supplement on growth performance, milk yield and composition, rectal temperature, respiratory rate, heart rate and some blood biochemicals of lactating cows during heat stress. Sixteen multiparous lactating Holstein cows (580±12 kg) were used in a change-over design with four treatments arranged in a 2×2 factorial experiment in 4 four-week periods (three weeks for treating followed by a week as gap). The treatments were two levels of drinking water temperature (chilled: 12°C and normal: 25°C), and two levels of potassium carbonate addition (0 and 0.96% of DM). Duration of the study was July to September with maximum and minimum ambient temperatures as 42 and 25 °C, respectively and overall temperature-humidity index value by 85.5. Feed intake of cows was measured daily. Blood samples were collected via tail vein at the final day of the periods. Rectal temperature, respiratory rate and heart rate were measured three times a period. Results showed that water temperature and potassium carbonate supplementation to diet had no significant effects on average daily gain, milk yield and composition, rectal temperature, respiratory rate, heart rate, blood urea nitrogen and ketene bodies levels of dairy cows during the experiment, but water temperature affected on feed intake where normal water caused an increase in feed intake of cows (P<0.05). Adding potassium supplement to diet had no significant effects on mentioned parameters but it decreased the respiration rate of cows (P<0.05). Generally, results showed that drinking water temperature did not affect on the physiological parameters but normal water can increase feed intake. Adding potassium supplement to diet only affected on the respiration rate of cows. The results of the study do not recommend the chilling of drinking water or adding potassium supplement to the diet of dairy cows under heat stress.

In this research, to estimate genetic parameters for the trait of milk production in Holstein cows resulted from American sperms, a total of 76,504 monthly test day milk records (three times a day milking) in 189 herd and calving from 2001 to 2012 were used. Test day milk records were genetically analysed by a random regression model. In the model, fixed effect of herd-year-season of calving (contemporary group), and covariables of age at recording and Holstein gene percentage were included. Orthogonal Legendre polynomials with third order were implemented to take account of genetic and environmental aspects of milk production over the course of the lactation. The results revealed that the average heritability for the second half of lactation period was higher than that of the first half. The heritability value for the second month was lowest (0.047) and for the tenth month of the lactation was highest (0.150). Gradual increase of genetic variation over the lactation and high residual variance in early months of the lactation were main factors affecting the heritability. High values for the repeatability of test day milk indicate that high accuracy could be expected as a cow is selected for later lactation based on her earlier records.

This study was carried out to determine the effect of different fatty acids (fatty acid profile) in close – up period on production performance, milk composition and blood parameters of lactating dairy cows. In this study, 15 Holstein cows were selected by the expected date of parturition (around 30 days before calving) and were randomly assigned in three groups with five cows. Three iso-nitrogenous diets differing in energy contents were fed in close up period. Experimental treatments were 1) control (without fat), 2) rumenprotected fat (RF) (saturated fatty acids) and 3) Roasted Soybean (RS) (unsaturated fatty acids). After calving, all cows were fed with similar diets. Cows’ performance, daily milk production, milk composition, dry matter intake, body condition score were recorded. Also blood samples were collected at 7 day intervals in -21, -14, -7, 1, 7, 14, 21 periods of calving. Dry matter intake and body condition score were not affected by fat supplementation. Corrected milk yield based on 3.5 and 4 percentage of fat and milk production, fat, lactose and protein production in cows that were fed fat diet were higher than control cows. But, the percentage of protein and lactose milk in the control group was higher than other groups. Glucose and cholesterol concentration in day of calving and cholesterol concentrate after calving in RS group was higher than RF group. Also glucose concentrate after calving in the control group was higher than RF group. The results indicate that rumen-protected fat and roasted soybean can be supplemented to dairy cows diet to increase milk production, Moreover, roasted soybean supplementation improve metabolic condition in dairy cows.

This study was conducted to determine the optimal level of lysine in grower diet of Japanese quail by using 360 day old quail chicks in a 2×6 factorial arrangement [two levels of metabolisable energy 2850, and 2950 Kcal/kg) and six levels of lysine (1.1, 1.2, 1.3, 1.4, 1.5, and 1.6%)] in completely randomized design with three replicates and 10 birds per each. Feed intake and body weight were measured weekly and feed conversion ratiowas calculated. The optimum level of dietary lysine was assessed using spline regression. The results showed that daily weight gain and feed conversion ratio were improved by increasing the dietary lysine (P<0.05). The optimum level of lysine for the best daily weight gain during 1-21 and 22-35 days of age were estimated 1.39 and 1.40 for the birds fed on diet containing 2850 Kcal/kg metabolisable energy and 1.34 and 1.35 for the birds fed on diet containing 2950 Kcal/kg metabolisable energy, respectively. According to the results of this study, the best growth rate and feed efficiency in Japanese quail could be obtained by feeding diets containing 2850 Kcal/kg energy, 26% protein and 1.39% and 1.40% lysine for 1-22 and 22-35 days of age, respectively.