Effect of thymol and carvacrol on nutrient digestibility in rams fed high or low concentrate diets

Published data on the effects of essential oils [EO] on in vivo nutrient digestibility in sheep are contradictory. In 2 experiments, the effect of thymol and carvacrol on nutrient digestibility was studied in sheep fed with high [70%] or low [52%] concentrate diets, using incomplete Latin Square designs. The essential oils were mixed with the concentrate portion of the diet at the rate of 0.0, 0.3, or 0.6 g per kg dry matter [DM] diet. Supplementation of thymol had no significant effect on digestibility of dry matter [DM], organic matter [OM], crude protein [CP] and acid detergent fiber [ADF]. The main effect of thymol on neutral detergent fiber [NDF] and ether extract [EE] digestibility and on nitrogen balance [NB] was significant [P<0.05], but within each level of dietary concentrate no significant differences were observed for these measurements. Overall, ruminal ammonia concentration was higher [P<0.05] in both HCD and LCD lambs receiving 0.3 mg thymol per kg diet. Supplementation of carvacrol had no significant effect on nutrient digestibility. The main effect of carvacrol on ruminal ammonia levels and NB was significant, but within each level of dietary concentrate no significant differences were observed in ammonia levels and NB. Inclusion of 0.3 g/kg diet DM of carvacrol or thyme was more effective than 0.6 g/kg diet DM in terms of NB but neither dose affected nutrient digestibility. Future research should determine the long-term effects of essential oils on digestibility and performance in sheep, before recommendation can be made for their use under practical husbandry conditions

[ relationship between growth hormone polymorphism and growth hormone receptor genes with milk yield and reproductive performance in Holstein dairy cows]

The aim of this study was to investigate the potential association between growth hormone GH/AluI and growth hormone receptor GHR/AluI polymorphisms with milk yield and reproductive performances in Holstein dairy cows in Iran. Blood samples of 150 Holstein cows were collected and their genomic DNA was extracted using Gene-Fanavaran DNA extracting kit. Fragments of the 428 bp of exon 5 growth hormone [GH] gene and the 342 bp of exon 10 growth hormone receptor [GHR] gene were amplified using the polymerase chain reaction [PCR] method. PCR products were digested by the AluI restriction enzyme and electrophoresed on 3% agarose gel. Continuous and categorical data were analyzed using linear mixed models through Proc MIXED and logistic regression models through Proc GENMOD of SAS software, respectively. The results showed no relationship between the examined traits and GH/AluI or GHR/AluI genes. A significant relationship was found between GH/AluI polymorphism and dystocia, but the presence of the GH-L allele reduced the incidence of dystocia. The results suggest that the GH-LL genotype reduces dystocia probably by affecting the release of growth hormone; nevertheless, further studies will be needed to examine the relationship between dystocia and GH genotypes.

Genetic correlation of average somatic cell score at different stages of lactation with milk yield and composition in Holstein cows

Genetic and non-genetic correlations of the average somatic cell score [SCS] at different stages of lactation [100, 150, 200, 305 and 365 days in milk] with lactation performance were estimated based on the first lactation records of Iranian Holstein calving during 2000 to 2009. [Co] variance components were estimated using derivative-free REML based on multiple traits animal models. The estimated genetic correlations between average of first 100 days in milk SCS [SCS[100]] and milk100, fat100, milk305, fat305 and protein305 were 0.14, 0.19, 0.11, 0.15 and 0.17, respectively. The corresponding environmental correlations were -0.13, -0.03, -0.18, -0.10 and -0.13, respectively. The estimated genetic correlations of the average SCS during the first 150 days in milk [SCS[150]] with milk[100], fat[100], milk[305], fat[305] and protein[305] were 0.14, 0.19, 0.11, 0.15 and 0.17, respectively. The corresponding environmental correlations were -0.13, -0.03, -0.18, -0.10 and -0.13, respectively. The estimated genetic correlations of the average SCS during 305 days in milk with milk, fat and protein yield, and fat and protein percentages were 0.12, 0.11, 0.18, -0.05 and -0.08, respectively. The estimated genetic correlation between SCS[100] or SCS[150] with average SCS over longer stages of lactations [SCS[305] and SCS[365]] was 0.99 +/- 0.01. These results indicate that recording SCS data over shorter period of lactation is an alternative approach to reduce the costs of SCS data collection and therefore to expand the SCS recording in the country by increasing both the number of herds and cows involved

Artificial insemination practice in British United Turkeys: a report in Iran

No domestic availability to breeder turkey stocks and turkey hatching eggs prompted the present experiment that aimed to evaluate the feasibility of a conventional artificial insemination [AI] procedure in British United Turkey [BUT] for the first time in Iran. Broiler turkeys were restrictedly fed, grown for 46 weeks, and used for the current study [10 turkey toms and 24 turkey hens in total]. After a 3 week period of habituating the toms to abdominal massage, the pooled semen was used for insemination after the dilution in sterilized and homogenized low-fat milk [at the ratio of 1 to 6]. The hens were inseminated [14:00 h] and hatching eggs were collected [n = 148]. All the eggs were broken open to assess the fertility rate. Although being lower than the conventional average fertility rate noticed for breeder turkeys in the production manuals [91%], a fertility rate of 61.5% was obtained. The present report provided a preliminary data on the feasibility of the conventional procedure used in chickens to artificially inseminate the turkey, using low-fat milk as a simple available extender. The present findings might also be promising to the future establishment of turkey breeder enterprise in Iran

[Association between the lactation curve shape and calving interval in Holstein dairy cows of Iran]

This study was carried out to investigate the relationship between early lactation curve parameters and calving interval in Holstein cows of Iran. In order to describe the lactation curve, the incomplete gamma function was fitted to 5,754,428 test-day milk records corresponding to 766,108 lactations on 315,634 cows in 2,448 herds. Cows with higher milk yield during early lactation had shorter calving intervals; however, longer calving intervals increased the 305-d milk production [P<0.01]. Cows with higher yield at the beginning of lactation, steeper ascending, and steeper descending slope had shorter calving intervals [P<0.01]. Calving interval was increased by 2.73 [+/- 0.12] d for every extra kg of milk at peak lactation [P<0.01]. The calving interval was directly impacted by the persistency of milk yield, but milk yield persistency was reduced in cows with shorter calving intervals [P<0.01]

effect of maternal inbreeding on incidence of twinning, dystocia and stillbirth in Holstein cows of Iran

The purpose of this study was to investigate the effect of maternal inbreeding on incidence of twinning, dystocia and stillbirth in Holstein cows of Iran. Calving records from March 2000 to April 2009 comprising of 365,021 calvings on 153,802 cows from 86 dairy herds were used. The mean level of inbreeding was 0.7%, less than 37% of all animals were inbred, and a small proportion [3.45%] of inbreed animals had inbreeding coefficients greater than 5%, with a maximum inbreeding coefficient of 38%. The overall average twinning and stillbirth rates were 2.7 and 3.78%, respectively. Dam parity and calving season significantly affected the incidence of twinning [P<0.01]. The twinning rate at parities 1, 2, 3, 4 and >/=5 were 0.72, 3.4, 4.51, 4.70 and 5.23%, respectively [P<0.01]. The incidence of stillbirth was significantly influenced by parity, calving season, calf sex and twinning [P<0.05]. Dystocia scores of >/=3 were less common amongst older cows. Gender of the calf was significantly associated with dystocia, whereas the incidence of dystocia was higher in dams delivering male calves [P<0.01]. First parity cows showed more difficult calving than higher parity cows [P<0.01]

The results indicated that the degree of maternal inbreeding presently observed in Iranian Holstein herds does not seem to have a significant effect on the twinning, dystocia and stillbirth rates?

Factors affecting stillbirth and effects of stillbirth on subsequent lactation performance in a Holstein dairy herd in Isfahan

The purposes of this study were to estimate the effects of risk factors on stillbirth parturition and evaluate the effects of stillbirth on lactation performance in Holstein dairy cows. Data were obtained from a dairy cattle herd located in Isfahan province, Iran. The logit of the probability of stillbirth was modeled using logistic regression and the effect of stillbirth on lactation performance was analyzed through mixed linear model using 12283 lactation records on 5201 cows. The results showed that 6% of the calves born die within 48 h of birth. The results of logistic regression analysis demonstrated that the frequency of stillbirth is significantly influenced [P<0.05] by calving year, parity number and calving difficulty. The stillbirth frequency was found to be significantly higher for first parity cows, [P<0.05]. Also, calving difficulty was shown to be significantly associated with increased risk of stillbirth [P<0.05]. Mixed linear model analysis results demonstrated that stillbirth significantly reduced milk and fat yield [P<0.05], but had no significant impact on milk fat percentage [P >/= 0.05]. The 305-d milk and fat yields for cows with stillbirth were estimated to be 8274.17 +/- 100.79 and 245.60 +/- 3.7 kg compared to 8865.60 +/- 88.16 and 259.36 +/- 3.2 kg for cows that had a live calf, respectively

[Bond strengths and debonding characteristics of ceramic and metallic brackets]

The risk of the enamel damage increases if the debonding fracture site shifts toward the junction between the enamel and adhesive. The aim of this study was to determine the in-vitro bond strength and the fracture site after debonding the mechanically-bonded ceramic and metallic brackets. Sixty extracted premolars were randomly selected from orthodontic patients in a private clinic. All the samples were divided into two groups and 30 metallic and 30 ceramic brackets were mechanically bonded to the teeth, using light curing adhesive. After one week, all the brackets were debonded by bracket-removing pliers assembled on a testing machine. This design simulated clinically-applied debonding compressive forces precisely. By the use of stereomicroscope and trans-illumination technique, the amount of adhesive remnant on the brackets' surfaces or on the teeth was evaluated and calculated using Photoshop and Auto Cat software program in the bonded areas in order to determine different fracture sites. Descriptive analysis was used to describe the findings and independent t-test was used to compare the differences between the two bracket groups. Debonding fracture was mostly observed in the interface between brackets and adhesive and within adhesive but there were no statistically significant differences in the location of the debonding fracture between the two groups. The risk of enamel damage after debonding both metallic and ceramic brackets is low due to the minimal chance of debonding failure between the enamel and adhesive