Iranian Journal of Animal Science Research
Year:2012 | Volume:4 | Issue:2|Papers Count:12

This experiment was carried out to evaluate the effect of Probiotic supplementation and feed restriction on growth response in broiler chickens. For this purpose, 336 male broiler chickens of Ross 308 were used. After housing, broilers allocated to experimental pens in a completely randomized design with factorial 2×3 arrangement. First and second groups considered as positive control group with supplemented probiotic or negative control group without supplemented probiotic, respectively, that birds in these groups had free access to feed. Four other groups used a diet same as control groups, but from 7 to 35 days of age subjected to 4 or 8 hours feed restriction. Four replicates of 14 birds were allocated to each experimental group. Results of the experiment indicated the birds subjected to feed restriction had significantly lower feed intake and body weight gain during the first week of rearing compared to those fed ad-libitum. There was no significant difference between experimental treatments for feed intake. In the group of without probiotic, feed restriction for 8 hours led to reduce weight gain and carcass weight compare to those fed ad-libitum. But when use probiotic, weight gain and carcass weight was similar to those birds were fed ad-libitum. The results of this experiment showed that the use of probiotic can improve the performance of broilers under severe feed restriction.

This experiment was carried out to evaluate the effect of different levels guar meal and b-mannanase on broilers male chicken. In this experiment, Four hundred Ross day old broiler chicks were randomly assigned to a 4×2 factorial design to feed broiler chickens diets containing guar meal at 4 level of guar meal (0, 3, 6 and 9%) with five replications of each treatment with or without b-mannanase. Ten chicks were assigned to each pen. The diets were based on maize-soybean meal were used: starter, 8-19 days; grower, 19-35 days; and finisher, 35-42 days. All starter, grower and finisher diets were formulated to have 21.5, 20.5 and 19% CP and 3050, 3100 and 3150 kcal/kg metabolizable energy, respectively. Average daily gain and daily feed intake were recorded over 19 and 42 days. Results indicated that addition of the guar meal to rations did not reduce body weight, feed consumption and feed conversion ratio. Enzyme supplementation did not significantly effect on body weight, feed consumption and feed conversion ratio. Relative weights of abdominal fat, thigh, gallbladder, liver and pancreas were not significantly affected by consumption of the guar meal at any level when compared with the control. Inclusion of the guar meal in the diet significantly decreased breast weight. The addition of b-mannanase to the diets significantly reduced ileal viscosity compared with the control group in 19 day. The results of this study show that replacement of guar meal up to 9% significantly with and without b-mannanase in broilers diet have no adverse effects on body weight, feed intake and feed conversion ratio, but leads to a reduction in breast weight. Guar meal can be used up to 3% of broiler diet with no adverse effect, but its high level (9%) reduced breast meat percentage.

One experiment was conducted with a total of 2000 broiler breeders (Lohman strain) at 74 weeks of age, which lasted for 10 weeks. Birds were randomly assigned to two dietary treatments varying in dietary crude protein (CP). The reduced-CP diet had dietary CP level approximately 1.5 percentage units lower than the control (15.5 vs 14.0%). By supplementing 0.13 and 0.1% of DL-methionine and L-HCl-lysine to the reduced-CP diet, respectively, the sulfur amino acids to lysine ratio was kept similar between the control and the reduced-CP diet. Data were subjected to one-way ANOVA in a completely randomized design with 2 treatments and 4 replicates. Results showed that egg shell thickness, hatchability, and the Hemagglutination Inhibision (HI) response against New Castle and Influenza from reduced-CP group were not significantly different from the control group. Hen-day egg production was also remained unchanged throughout the experiment. Nevertheless, it was numerically higher in the low-protein group than the control group. In conclusion, egg production, hatchability and the immune response of broiler breeders can be maintained on a reduced-CP diet (90% of the industry norm) when the contents and ratio of sulfur amino acids to lysine kept constant.

The effect of lavender essential oil (LEO) on broiler performance, carcass characteristics and blood metabolites was examined in a completely randomized design with 5 treatments (control diet, virginiamycin 10% (50 ppm) and 3 diets containing 150, 250, 350 ppm lavender essential oil) and 5 replications in a period of 42-days. No significant differences were noticed for feed intake between the treatments. Birds receiving diet containing 350 ppm LEO showed the highest weight gain and the control diet lowest weight gain. From weeks 3 to 6, the feed conversion ratio was significantly better in the group receiving 350 ppm LEO than other groups. There were no significant differences between treatments for serum cholesterol, triglyceride, HDL, LDL, VLDL, mortality and carcass characteristics at the end of experiment. The diet with 350 ppm LEO increased serum calcium level significantly (P<0.05). These results showed that LEO could be considered as a potential natural growth promoter for broiler chickens. It appears that the response may be dose-related and higher levels may be needed to elicit this response. However, more experiments are needed in this content.

In order to examine the effect of using rumen protected methionine (Mepron, Evonik Industries, Hanau, Germany) on productive and reproductive performance under field condition, 195 Holstein cows were used in a unbalanced completely randomized design and 2 groups. Experimental treatments consisted of: 1) control group with 110 Holstein dairy cows (71±51 DIM and 47.5±12 milk yield) and without Mepron and 2) experimental group with 85 Holstein dairy cows (85±59 DIM and 47.0±12 milk yield) and 13 g Mepron per cow/d. Cows were group fed with TMR and 4 times a day. The diets were balanced with AminoCowÒ soft ware. Using Mepron decreased CP content from 17.05% in control group to 16.47% in experimental group, while other nutrients were simila r between two diets. Adding Mepron to diet resulted in a significant increase in dry matter intake (P<0.01; 25.8 vs.26.6 kg/d) and a decrease in daily feed cost per cow (70820 vs.69180 Rials). Milk yield and lactose percentage did not affect but a tendency was detected for more protein percentage (P<0.13; 3.02 vs. 3.10) and lower fat percentage (3.15 vs.3.08) in experimental group. Decrease in milk urea nitrogen (MUN) in experimental group compared with control tended to be significant (P<0.17; 18.8 vs.17.6 mg/dl). Pregnancy rate increased 13% in experimental group compared with control group (41.8 v s. 45.9%). These results show positive effects of feeding rumen protected methionine under field condition on improving productive and reproductive performance.

The present study was conducted in order to determine the effects of feeding frequency (FF) on dairy co w performance fed a total mixed ration (TMR) based on chopped alfalfa hay. Eight multiparous early lactation Holstein cows were housed in the individual boxes (4 x 3 m) and fed either once a day (Ix) at 0700 h or 4 times a day (4x) at 0100, 0700, 1300 and 1900 h with TMR. The experiment was done as a 2 x 2 crossover design with two 20-d periods. When FF changed from 4x to lx, dry matter intake (21.1 vs. 20.0 kg/d) and NEL intake (36.4 vs.34.3 Mcal/d) increased (P<0.005). There was no difference between treatments in percentage of remained feed to supplied TMR ratio (7.6 vs. 10%), milk yield (31.5 vs. 30.7 kg/d), milk NEL output (21.7 vs.21.4 Mcal / d), fat content (3.5 vs.3.6%), protein content (3.2 vs.3.2%), milk NEL to intake NEL ratio (0.60 vs. 0.62), and fecal pH (6.64 vs. 6.62). Urine pH was higher in 4x compared with lx group (8.12 vs. 8.00), and serum insulin tended to be higher (10.9 vs. 6.9mIU/ml) for4x group. Serum free fatty acids (0.45 vs.0. 0.56mIU/ml) increased by 4x vs. lx. Generally, results showed that under uncompetitive individual feeding and housing, increasing feeding frequency does not have any productive and metabolic advantages.

This experiment was conducted to assess the effects of daytime cutting management (p.m. vs. a.m. cut), ensiling duration and adding microbial inoculants on chemical composition of alfalfa silage. For this, Second growth Alfalfa harvested at the early bud stage of development after a sunny day at sundown (about 1900 h; PM alfalfa), whereas the second half was cut next day at sunup (about 0800 h; AM alfalfa). After cutting, alfalfa Forage was chopped by using a chopper to a length of 8 to10 cm, and then ensiled without or with microbial additive as factorial experiment (2×2) with repeated measurement design. Silages were provided in laboratory silos (6 repeats in every treatment) lined with two layers of plastic, after air exclusion. Silos were opened at 3, 10 and 30 day for determination of pH and other chemical analysis. The numerically lower pH of PM vs. AM silages indicates that the former forage was more extensively fermented possibly because of its increased total non structural carbohydrate (TNC) concentration. Shifting alfalfa harvesting from sun up to sundown significantly decreased NDF% and ADF%, because of the dilution effect associated with increased concentrations of TNC in the former forage. The NPN content and N-NH3 concentration of the silages treated in the afternoon was lower compared with AM group. CP content decreased, but NDF, ADF, NPN and N-NH3 concentration increased during ensiling time. Silage pH decreased by using of microbial additive and ensiling time. Dry matter and nitrogen losses were lower in silages treated by microbial inoculants, and, increased with increasing fermentation time. It can be concluded that microbial additives and time of cutting can be used as proper way to improve fermentation situation and silage quality.

In this research in order to estimate genetic parameters for milk yield at different milking times for Holstein cows of Razavi Khorasan, a total of 180, 462 monthly test day records belonging to first lactation cows calved from 2000 to 2009 were utilized. The records were analysed by a random regression test day model. In the model, the fixed effects of contemporary group of geographical location-herd-year of recording-production season-sperm type, linear covariables of Holstein gene percentage, age at recording, as well as additive genetic and permanent random effects were included. For morning (M1) and night (M3) milking times, maximum additive genetic variances were found in month eight (0.808 and 0.659, respectively) while the minimum value (0.399 and 0.319, respectively) was found for both milking times in month two of the lactation curve. Maximum and minimum additive genetic variances for noon (M2) milking times were observed in months ten (0.732) and two (0.278), respectively. Permanent and residual variance components were the greatest values at the end of the lactation course. Maximum heritability estimates of M1, M2 and M3 were found to be 0.143 (month eight), 0.137 (month nine) and 0.139 (months eight and nine), respectively. For all milking times, minimum additive genetic correlations were found between month one and month eight and ranged from 0.216 to 0.285, while the maximum values were observed between month six and month seven and ranged from 0.993 to 0.996. For all milking times, permanent environment correlations were maximum between months five and six (ranged from 0.992 to 0.993) and minimum between months one and ten (ranged from 0.411 to 0.445).

In order to evaluate paternity test using microsatellite markers, a small sample of Iranian Holstein cattle population including 8 unknown individuals without any given prior knowledge on their genetic relationships were tested using 12 microsatellite loci recommended by International Society of Animal Genetics (ISAG). They were genotyped by a multiplex PCR set consisted all 12 fluorescently labeled primer pairs. Allele and genotype frequencies were estimated and simulated by CERVUS 2.0 software for paternity analysis. Using this software parentage test and relationship between samples have been determined and confirmed by sample’s provider. Paternity relationship including one or two parents for an offspring and also repeated samples were observed. The average expected heterozygosity of 11 analyzed loci and the mean value for PIC was 0.72 and 0.631 respectively. Except TGLA53 locus that was excluded from further analyses due to low quality of alleles and genotype detection, total exclusion probability of 11 loci showed that the paternity test using microsatellite loci mentioned here can be successfully implicated in large scale in Holstein dairy cattle population in Iran.

In order to analyse the effects of some environmental factors on milk production characteristics of Holstein cows in dairy farms of Mashhad, a total of 46, 420 test day milk records belonging to 5, 323 first lactation cows calved between 1994 and 2007 were utilised. First, Gompertz non-linear function was fitted to test day milk records of individual cows using SAS software. Then, based upon the estimated parameters of the function, milk porduction characteristics including time to peak yield (TM), milk yield at peak time (YM), lactation milk yield (YL) and initial milk yield (Y0) were calculated. Analysis of the environmental factors for the traits was carried out through a set of linear mixed models. The fixed effects of herd, year, season of calving and sperm type were significant on all the traits. Holstein gene percentage had significant influence on YL, PT and Y0. Calving age had only significant affect on YM and Y0. The effect of days open was significant for YL, YM and TM. There were positive and significant annual phenotypic trends for YL (10.27 kg), YM (0.43 kg) and TM (2.84 d).

In this research a random regression test day model was used to estimate heritability values and calculation genetic correlations between test day milk records. a total of 140357 monthly test day milk records belonging to 28292 first lactation Holstein cattle (trice time a day milking) distributed in 165 herd and calved from 2001 to 2010 belonging to the herds of Tehran province were used. The fixed effects of herd-year-month of calving as contemporary group and age at calving and Holstein gene percentage as covariate were fitted. Orthogonal legendre polynomial with a 4th-order was implemented to take account of genetic and environmental aspects of milk production over the course of lactation. RRM using Legendre polynomials as base functions appears to be the most adequate to describe the covariance structure of the data. The results showed that the average of heritability for the second half of lactation period was higher than that of the first half. The heritability value for the first month was lowest (0.117) and for the eighth month of the lactation was highest (0.230) compared to the other months of lactation. Because of genetic variation was increased gradually, and residual variance was high in the first months of lactation, heritabilities were different over the course of lactation. The RRMs with a higher number of parameters were more useful to describe the genetic variation of test-day milk yield throughout the lactation. In this research estimation of genetic parameters, and calculation genetic correlations were implemented by random regression test day model, therefore using this method is the exact way to take account of parameters rather than the other ways.

In order to study the effect of male on reproductive behavior of female goats, 88 Markhoz breed goats with initial body weight of 42±2kg, 3.5 year old, and 10 male goats were used for 6 weeks. This study was conducted in two phases. In the first experiment 48 female goats were allocated in three groups, each group included eight animals with 2 replicate on both sides of male goats, respectively, at intervals of 0-5, 10-15 and 25-30 meters. In the second experiment, 24 female goats having CIDR were used in an order similar to that of first group. However, the goats were located only in one side of the males. The third group was the control group which was treated in a separate saloon in two groups, each of them having eight animals in it. Results showed a significant effect of male animal in estrus synchronization, the earlier beginning of the reproductive cycle and fertility in the early reproductive season. The first group showed better results in creation and synchronization of estrus in comparison to CIDR received animals (respectively 116.7 vs. 91.6%).