مجله تحقیقات دام و طیور
سال سوم شماره 4 (1393)

This experiment was conducted to investigate the effect of processing with low steam pressure, sulfuric acid and Natozyme enzyme mixture on digestibility and in vitro gas production parameters of sesame straw. Experimental treatments were two levels of 0 and one bar steam pressure in 120 min and 130 °c, two levels of 0 and 2.4% sulfuric acid, and two levels of 0 and 3 gr/kg/DM exogenous enzyme. Chemical composition, in vitro digestibility and gas production parameters of the samples were determined. Processing caused to significant decrease of dry matter, crude protein, neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin content of sesame straw (P< 0.05). Processing by acid, steam and enzyme decreased the lignin by 4%. Processing by water decreased the ADF content of samples from 46.89% in the control treatment to 26.48%. Processing influenced gas production, cell wall degradability and digestibility of neutral detergent fiber (P<0.05). The greatest potential of gas production (53.55 mL) was related to the sesame straw processed by acid - steam - enzyme and the greatest rate of gas production (0.0283 ml/h) was belonged to the sesame straw processed by steam– enzyme. Sesame straw processed by acid- steam- enzyme had the greatest digestibility of NDF (55.45%) and ADF (45.83%).Therefore the result of this experiment showed processing of sesame straw by acid- steam- enzyme had the best effect on decrease of lignin content of samples. Also cell wall degradability, potential of gas production, microbial biomass and digestibility of ADF and NDF of sesame straw processed with this treatment was more appropriate than the other treatments.

This experiment was conducted to determine the effects of sodium bentonite on broiler growth parameters, and to compare prediction ability of the Gompertz model and artificial neural network (ANN). A total of 288 one day-old Ross chicken were used in a completely randomized design with 6 treatments (6 diets) and each treatment were divided into 4 replicates. The treatments were diets including 0, 0.75, 1.5, 2.25, 3 and 3.75% sodium bentonite, which was used as top-dress. Gompertz growth function was used to estimate the growth characteristics and to compare the prediction ability of this function with artificial neural network, R square coefficient (R2), mean absolute deviation (MAD), root mean square error (RMSE) and bias were used as indicators. The treatments caused significant changes in the final weight (Wf), the initial weight of chicks (W0), the time for change of growth curve (T) and the weight in the change of growth curve (Wi) (P<0.05), but constant of exponential growth (b) was not affected by the experimental diets. Growth rate at all ages, except the fourth week, was affected by dietary treatment (P<0.05). The R square coefficient for the artificial neural network (0.9992) was higher than Gompertz equation (0.9925. The value of the MAD, RMSE and bias of ANN was less than the Gompertz equation. Overall, this experiment shows that the performance of the ANN for estimation the weight of broilers at 42 days-old was better than Gompertz equation.

Growth traits in farm animals are of great economic importance. Today, growth rate, body weigh changes at different stages of the life, is considered as an important trait in animal breeding. Growth process can be described by a nonlinear function. In the present study, to describe the growth curve of different breeds of Iranian sheep, Gompertz nonlinear function was fitted on body weight records of 134,798 lambs (born between 1985-2010) from birth to 72 months of age. The lambs were progeny of 5,198 rams and 82,577 ewes in a total of 541 flocks. Growth curves of the breed, year and season of birth, sex of lamb, type of birth and dam age were predicted by using estimated parameters of the function. The findings showed Lori-Bakhtiari and Kermani breeds had highest (37.126 kg) and lowest (21.078 kg) mean body weight, respectively. Male lambs were found to be heavier than female lambs (29.956 kg vs. 27.921 kg). Older ewes (parity five and over) had heavier lambs than that of the younger ewes. The highest and lowest mean body weights were obtained for singleton (28.812 kg) and triplet (27.036 kg) lambs, respectively. Gompertz could provide a descriptive comparison for animal growth and to be utilised for predicting growth rate.

This experiment was conducted to investigate the effect of harvesting, addition of formic acid and ruminal fluid to sorghum silage on amount of gas production. Sorghum at the first and second harvesting (with 25 % DM) was treated with formic acid and rumen fluid and then was ensiled for 81 days. After opening and drying the samples, a sample was taken from each treatment and put it into gas production syringe. Gas production at 2, 4, 6, 8, 16, 24, 48, 72 and 96 hours of incubation were recorded. Results showed that for the second-cut silage gas production was lower and that coefficient b was higher as compared to the first-cut silage. In the second experiment, gas production for the silage treated with ruminal fluid was significantly lower than the control treatment and a higher b coefficient was also found for the formic acid treated silage. Organic matter digestibility (OMD) and metabolism energy (ME) were greater for the first-cut as compared to the second-cut silage. Treating the silage with ruminal fluid caused a significant decrease of OMD (45.73 % vs. 52.1 and 52.59 %), ME (6.72 MJ/kg DM vs. 7.7 and 7.75 MJ/kg DM) as compared with formic acid and control treatments.

The study was carried out to evaluate the polyphenol content, chemical composition, radical scavenging activity and inhibition potential of peroxidation of pomegranate seed and other agricultural by-products such as tomato, apple, lemon and orange pomace in comparison with alfalfa, ascorbic acid, alpha-tocopherol and butylated hydroxyl toluene (BHT) as common antioxidant source of diet. Effect of temperature and duration of oxidation on peroxide value of raw soybean oil were investigated as food processing simulation. The results indicated that peroxide value of soybean oil samples increased by rising temperature and time of oxidation significantly. Total saturated and unsaturated fatty acid contents of oil significantly increased and decreased by oxidation, respectively. The pomegranate seeds methanolic extract had the highest values of polyphenol, radical scavenging activity and inhibition potential of peroxidation among all investigated materials. Pomegranate seeds had notably high fiber, CP, EE, Cu, and Zn content and acidifying potential compared with other investigated by-products. Therefore, pomegranate seed seems to be effective antioxidant and beneficial supplement for peri-parturation period from metabolic point of view.

Prolificacy trait of Iran black was compared with Baluchi and Arman sheep breeds and the environmental factors affecting the trait were studied. Furthermore, estimation of genetic parameters and evaluation of the genetic trend of the Iran black breed for the prolificacy and average birth weight of the lambs per lambing (as a trait for the ewes) were carried out using bivariate (linear-threshold) repeatability model. Total recorded animals was 2,701 (offspring of 110 sire and 840 dam) and the data were collected during 1980-2009 by Abbas Abad breeding station that located in Mashhad, Iran. Lambing rate was significantly higher in Iran black and Arman breeds than in Baluchi breed (P<0.01). Lambing rate decreased with aging of the ewes, such that, ewes older than 8 years old showed the lowest prolificacy. Ewes with age between 2 to 6 years did not differ to each other significantly. Heritability of average birth weight of the lambs and prolificacy were 0.148 and 0.266, respectively. Repeatability estimates of the traits were 0.674 and 0.381, respectively. Phenotypic, environmental and genetic correlations among the traits were highly negative and were -0.484, -0.369 and -0.968, respectively. The genetic trend for the prolificacy trait was ascending until year 1996 (0.016 lamb/year) and descended afterwards (-0.012 lamb/year). Genetic trend for average birth weight of the lambs were opposite in direction with genetic trend of prolificacy in both periods. It seems that lack of a sustainable breeding strategy for genetic improvement of Iran Black breed for prolificacy and other economically important traits has resulted in a non-constant genetic progress during the past years.

A total of 224 Leghorn laying hens at 60 weeks of age were randomly assigned into seven dietary treatments and four replicates each one with eight birds in each replicate. The hens were fed with diets including: Negative Control (without Ca sources, phytase and organic acids supplementation); Negative Control with Ca-carbonate; Negative Control with limestone; Negative Control with Ca-carbonate and phytase; Negative Control with limestone and phytase; Negative Control with Ca-carbonate, phytase and organic acids and Negative Control with limestone, phytase and organic acids. Feed intake significantly was lower in experimental diets than the negative control. Mean egg weight in all experimental diets was higher than the negative control (P<0.001). The hen-day egg production was higher in all dietary treatments than the negative control (P<0.01). Also, negative control with phytase or organic acid supplementation diet was better than the treatment without phytase and organic acid. Feed conversion ratio was better in all dietary treatments than the negative control (P<0.001). Eggshell quality parameters were better in all dietary treatments as compared to negative control (P<0.05). The results showed that inclusion of either Ca sources or feed additives could improve layer performance and eggshell quality in commercial laying feeds.