The effect of maternal nutrition level during the periconception period on fetal muscle development and plasma hormone concentrations in sheep.

The effect of maternal nutrition level during the periconception period on the muscle development of fetus and maternal-fetal plasma hormone concentrations in sheep were examined. Estrus was synchronized in 55 Karayaka ewes and were either fed ad libitum (well-fed, WF, n=23) or 0.5×maintenance (under-fed, UF, n=32) 6 days before and 7 days after mating. Non-pregnant ewes (WF, n=13; UF, n=24) and ewes carrying twins (WF, n=1) and female (WF, n=1; UF, n=3) fetuses were removed from the experiment. The singleton male fetuses from well-fed (n=8) and under-fed (n=5) ewes were collected on day 90 of gestation and placental characteristics, fetal BWs and dimensions, fetal organs and muscles weights were recorded. Maternal (on day 7 after mating) and fetal (on day 90 of pregnancy) blood samples were collected to analyze plasma hormone concentrations. Placental characteristics, BW and dimensions, organs and muscles weights of fetuses were not affected by maternal feed intake during the periconception period. Maternal nutrition level did not affect fiber numbers and the muscle cross-sectional area of the fetal longissimus dorsi (LD), semitendinosus (ST) muscles, but the cross-sectional area of the secondary fibers in the fetal LD and ST muscles from the UF ewes were higher than those from the WF ewes (P<0.05). Also, the ratio of secondary to primary fibers in the ST muscle were tended to be lower in the fetuses from the UF ewes (P=0.07). Maternal nutrition level during the periconception period did not cause any significant changes in fetal plasma insulin and maternal and fetal plasma IGF-I, cortisol, progesterone, free T3 and T4 concentrations. However, maternal cortisol concentrations were lower while insulin concentrations were higher in the WF ewes than those in the UF ewes (P<0.05). These results indicate that the reduced maternal feed intake during the periconception period may alter muscle fiber diameter without affecting fiber types, fetal weights and organ developments and plasma hormone concentrations in the fetus.

Estimates of phenotypic and genetic parameters for birth weight of Brown Swiss calves in Turkey using an animal model.

A study was conducted to assess the influence of genetic and environmental factors on Brown Swiss calf birth weight, and to estimate variance components, genetic parameters, and breeding values. Data were collected on 1,761 Brown Swiss calves born from 1990 to 2005 in the Konuklar State Farm in Turkey. Mean birth weight for all calves was 39.3 ± 0.09 kg. Least squares mean birth weights for male and female Brown Swiss calves were 40.3 ± 0.02 and 39.0 ± 0.02 kg, respectively. Variance components, genetic parameters, and breeding values for birth weight in Brown Swiss calves were estimated by restricted error maximum likelihood (REML)-best linear unbiased prediction(BLUP) procedures using an MTDFREML (multiple trait derivative free restricted maximum likelihood) program employing an animal model. Direct heritability (h(d)(2)), maternal heritability (h(m)(2)), total heritability (h(T)(2)), r(am) and c(am) estimates were 0.12, 0.09, 0.23, -0.58, and -0.06, respectively. The estimated maternal permanent environmental variance expressed as a proportion of the phenotypic variance (c(2)) was 0.05. Breeding values were estimated for the trait and used to evaluate genetic trends across the time period investigated. The genetic trend linear regression was not different from zero. No genetic trend for birth weight was expected, since there had been no direct selection pressure on the trait. Absence of a trend confirms that there was no change due to selection pressure on correlated traits. Genetic and environmental parameter estimates were similar to literature values indicating that effective selection methods used in more developed improvement programs would be effective in Turkey as well.

Effects of housing systems on growth performance, blood plasma constituents and meat fatty acids in broiler chickens.

A research was conducted to determine the influence of the conventional and the free-range broiler housing systems using female broiler chicks had low hatching weight on growth performance, breast meat characteristics and some blood plasma parameters. In the conventional (totally confined) housing system sixty one-day-old female Ross broiler chicks were placed in indoor floor pens with three replicates of 20 chicks. In the free-range (partly-confined) housing system, sixty one-day-old Ross broiler chicks were placed in indoor floor pens and also accessed to a grass paddock during 44 day experimental period after 7 days old. Birds of both systems were fed the same commercial broiler diet. The free-range housing system significantly decreased the total feed intake and body weight of broilers (p<0.05). The redness (a* color) and yellowness (b* color) in breast meat were affected by the housing systems (p<0.05). The housing systems had no affect on fatty acids composition of breast meat (p>0.05). The plasma triglyceride and VLDL levels of the conventional reared birds were significantly higher than those reared the free-range (p<0.05). In conclusion, longer growth period was necessary to the free-range reared broilers.