نشریه علوم دامی (پژوهش و سازندگی)
پیاپی 89 (زمستان 1389)

The objective of the study was to decrease weaning age of calves kept under rural condition in order to reduce the cost of feeding calves in Shahrood area (located in Semnan province). One hundred forty-four calves were randomly assigned to a 3 2 factorial arrangement including 3 weaning age (60، 75 and 90 days) and sex (male and female). All calves were fed with a controlled diet from birth till 3 months of age and were fed ad-libitum from 3 to 6 months of age. Those calves belonged to treatments with weaning at 60 and 75 days، had received a starter diet till 3 months of age too، and the other calves consumed milk till 3 months of age. All the calves had open access to alfalfa. The calves were fed from 3 to 6 months of age with similar diet to evaluate the effects of the first period on the next growth. Consumption of milk، starter diet and alfalfa were calculated for each calve during the first period، and all the calves were weighted from born until 6 months of age monthly. Average daily weight gain of calves was not significant between first، second and the third months but was significant for fourth months، while the calves were weaned at 60 and 75 days of age showed higher weight gain in comparison with those were weaned at 90 days of age. Average daily weight gain of calves was decreased in third treatment during fourth month but was compensated in fifth and 6th months. As differences for average daily weight gain of calves were not significant between treatments from birth until six months of age، So، it could be suggest that in rural condition، it is possible to wean calves at the age of 2 months instead of 3 months or more، by using a starter diet from two weeks of age.

This study was conducted to determine the chemical compositions، invivo and invitro digestability of dry matter (DM)، organic matter (OM) of four varieties of canola straw. The degradability of DM and crude protein (CP) were determined by Dacron-bag technique on two ruminally fistulated cows. The invivo digestibility coefficients for DM، OM، CP and CF were %48. 3، %50. 6، %39. 3 and %59. 3 respectively. The invitro digestibility coefficients of DM،OM and DM/OM were %37. 8، %31. 6 and %28. 9 respectively. The results indicated that there were no significant different between these canola strow varieties except for energy and zinc. The effective degradability of DM of Licord، Ocapi، Talaei1 and Talaei2 were %47. 1، %44. 4، %42. 6 and %42. 2 respectively (p<0. 05).

In order to determination values of six important range dominant plants species in sand dunes of Khouzestan. Studied species included: Stipagrostis plumosa، Pennisetum divisum، Panicum antidotale، Asthenathrum forsskalii، Medicago Laciniata، Convolvulus oxyphyllus at two phonological stages (Vegetative growth and full flowering) in sand Dunes of Khouzestan was studied. The samples were dried under shade condition and then measured chemical composition and comprised them: crud protein، crud fiber، ADF، ashes، Phosphorus، Calcium، metabolism energy and digestible dry matter. Data were analyzed by using split plot experiment at randomized complete block design and Duncan’s test. The results of variance analysis showed that amounts of crude protein، digestible dry matter، metabolism energy and ashes were decreased with increasing growing season but crud fiber and ADF were increased. The crude protein was highest percentage in Medicago lacinaita and lowest percentage was in Pennisetum divisum. The lowest changes of crude protein at two phenological stages were in Medicago laciniata but the highest changes showed in Pannicum antidotale. The amounts of calcium and phosphorus were decreased with increasing growing stages.

576 day old chicks from ARIAN 386 were selected according to there’s weight in 14 days of breeding. Experimental groups were consisted of 4 groups،1) control (without restriction)، 2) restriction1 (from 6 AM to 1 PM an hour’s feed allowance and 3 hours restriction)، 3) Restriction2 (from 6 AM to 1 PM an hour’s feed allowance and 4 hours restriction)، 4) Restriction 3 (from 6 AM to 1 PM at first and end of the time 3 hours restriction after an hour’s feed allowance and in 2 within time 5 hours restriction) with 4 replicate and 36 chicks (18 male+18 female). Feed intake، body weight gain، mortality، feed conversion were measured weekly. At the end of the experiment carcass percentage، breast (%)، leg and abdominal fat were measured with 10 birds (5 male and 5 female) from each pen. Data were analyzed by completely randomized design. Body weight in 21 days reduced by Feed restriction (p>0. 05)، but this reduction were compensated later and the weight of restricted chicks in 49 days were higher than control groups. Feed consumption in restricted group of 21 was lower than control but total feed intake in slaughtering time had no difference. Feed conversion was improved by restriction (p>0. 05). Feed restriction had no significant effect on carcass quality (p>0. 05).

In order to determination of nutritive value of Lathyrus sativus at four stages of growth، an experiment carried out in Chalaki research station located in the west of Gorgan. This experiment was a completely randomized design by five replications. Stages of growth consisted of: vegetative growth، mid-flowering (50%)، milky seed and milky-dough seed. Dry matter (DM)، crude protein (CP)، ether extract، ash، gross energy (GE) and acid detergent fiber (ADF) were measured in the laboratory. So، digestibility dry matter (DDM) and total digestible nutrient (TDN) were calculated with accounting formula. Result of the analysis showed that DM and ADF concentration increased when plant age increased and reached to doughy stage (P<0. 05). In contrast، DDM and TDN decreased as age increased (P<0. 05). Gross energy and organic matter content were not significant different at four stages. The highest percentage CP and EE were observed in mid-flowering stage (P<0. 05). The results shown that lathyrus sativus had suitable nutritive value and the best stage for forage harvesting is mid-flowering.

This study was conducted to evaluate effects of enzyme (Saphyziyme) supplementation in wheat-based layer diets on hen performance and egg quality traits. A total of 288 Hy Line (W-36) laying hens (aged 62 to 74 weeks) were distributed in a completely randomized design in a 4×2 factorial arrangement (4 levels of wheat، 0، 22، 44 and 73. 77% and 2 levels of enzyme، 0. 7 and 1. 4 g/kg) and were fed with one of 8 dietary treatments. The results of this study did not show any significant differences in percentage of egg production، egg mass and feed conversion between dietary treatments. A higher egg production and egg mass، and a better feed conversion ratio were observed in experimental group with 22% of wheat grain which were statistically non-significant. The highest amount of egg weight (64. 06 g) was belong to control group (corn- soybean meal based diet) (P<0. 05). Using 1. 4 vs. 0. 7 g of enzyme/kg of diets improved all quantitative traits (egg production percent، egg weight، egg mass production and feed conversion). It was concluded that replacement of corn by wheat did not have any adverse affects on performance and egg quality traits، except for egg weight، of laying hens (P>0. 05).

A total of 159، 465 monthly test day fat yield records belonging to 18،808 Holstein heifers were used to estimate genetic parameters. The data were collected between 1993 and 2007 from the herds over the Khosrasan provinces. Two test day models، fixed and random regression models، were used to estimate genetic and phenotypic parameters. In both models، fixed environmental factors of herd- year- season- milking times، and the covariates of age at recording as well as Holstein gene proportion were included. To take account of additive genetic and permanent environmental variation، the cow numbers were also included in the model. Legendre polynomials were utilised in both models for accounting for fat yield variation over the course of the lactation at phenotypic and genetic levels. SAS programme was used to study the effects of environmental factors and DFREML was applied to estimate variance and covariance components in test day models. The results showed that average heritability and repeatability of monthly test day fat yield were 0. 08 and 0. 318 respectively for random test day model while the corresponding figures were found to be 0. 059 and 0. 233، respectively for fixed test day model. Average genetic، phenotypic and permanent environmental correlation of monthly test day milk fat yield were 0. 728، 0. 229 and 0. 728، respectively for random test day model.

Repeated measures experiments have been used commonly in animal science for a long time، but only in recent years there have been big developments in methodological and computational issues that permit to analyze them effectively. Models and analyses of repeated measurements differ substantially from classical analyses. The many types of softwares are available in recent years to overcome disadvantages of the fitting models with repeated measurements. In this study repeated measurements from growth traits data of a Makoei sheep population were modeled by different variance-covariance structures. The models were compared by using Akaike’s Information Criterion (AIC)، AIC corrected for small sample sizes (AICC)، -2 Restricted log Likelihood (-2Res logL) and Bayesian Information Criterion (BIC). The “unstructured covariance (UN)” structure was chosen as the best structure for the data set. Furthermore، the most valid and the smallest standard errors were obtained using UN structure.

This paper carried out to investigate ecological and economical services value of honey bees using Robinson et al (1989) and Mors and Calderon (2000) model in Khorasan Razavi province. Results showed that direct products value of honey bees is equal to 68 billion rial. Ecological value of it is 9721 billion rial that it is approximately 143 fold of direct product value. The share of crop products، garden products and nitrogen stabilization of total ecological services value are 5479085، 4241986 and 417 million rial، respectively. Based on estimates، ecological services value of honey bees (pollination and nitrogen stabilization services) conclude about 30% of value added of agricultural sector and 8% of national gross product of Khorasan Razavi province. Direct products value of it (honey and beeswax production) is only 0. 48% of value added of agricultural sector and 0. 05% of national gross product of Khorasan Razavi province. Regard to results، try to promotion of farmers’ awareness to advantages of pollination through extension services، increase the colony capita of gardens and farms for closing to world standards and include of this estimates to calculating of domestic gross products of Khorasan Razavi province suggested.

Inattention to physiological changes due to selection، have increased the risk of behavioral، physiological and immunological syndromes in the species under selection. The current study was conducted to determine the effect of divergent selection for 4-wk body weigh on carcass composition and blood parameters in Japanese quail. Within seven generation different quail lines including two divergently selected lines for high and low 4-wk body weight (HW and LW respectively) and a control line (C) were generated. The blood samples were collected from birds randomly chosen from each line at 32 and 42 day of age، and then birds were slaughtered for carcass compartments and visceral organs comparisons. Although the female quails in LW line were heavier than males (P<0. 05) from 24 day of age hereafter، however، the results of current study indicated that there was no significant difference between male and females body weight in HW and C lines during the growth period. The growth pattern of three line were significantly different The birds in HW line showed heavier carcass، breast، thigh and heart weight than the LW line (P<. 05). Moreover the plasma cholesterol level of the birds in HW line were higher than that in LW and control lines (P<. 05) (P<. 05).، The results current study indicated that at short term، divergent selection for 4 week body weight can change the growth pattern and the carcass compartments of the selected birds. To avoid of undesirable side effects due to selection in Japanese quails it is recommended to consider the growth pattern changes of the selected birds in the breeding selection strategies.