Mehmet Kuran

The effect of maternal nutrition level during mid-gestation on postnatal muscle fibre composition and meat quality in lambs

Maternal nutrient intake during early- and mid-gestation can alter fetal growth and development with long-term consequences on the postnatal productivity and health of offspring. The aim of this study was to investigate the effects of maternal nutrition level during mid-gestation on postnatal growth rate, carcass composition, muscle fibre characteristics and meat quality in lambs. Ewes were fed from Days 30 to 80 of gestation as follows: 100% (control group, C), 50% (undernutrition, UN) or 175% (overnutrition, ON) of their daily requirement. During the rest of the gestation, the ewes in all groups were fed 100% of their daily requirements. Birth and weaning (at Day 90) weights of lambs born to ewes in nutritional groups were similar, but slaughter weights (at Day 150) and daily weight gain during finishing period of lambs born to the UN group were lower (P < 0.05). Similarly, a decrease in weights of semitendinosus (ST), semimembranosus and gastrocnemius muscles was observed in the lambs born to the UN group (P < 0.05). Lambs born to the ON group had a higher (P < 0.05) concentration of DNA in longissimus dorsi (LD) and ST muscles than UN groups, but they had a lower (P < 0.05) total protein and other proteins concentrations in LD and ST muscles than those to C and UN groups. Protein to DNA ratio in LD and ST muscles of lambs born to ON group were lower than those to C and UN groups (P < 0.05). However, lambs born to the ON group had a higher number of Type IIA and IIB muscle fibres in ST muscles but not in LD muscles than those in the C and UN groups (P < 0.05). Additionally an increase in the number of fibres/mm2 muscle area in lambs born to the ON group was observed in LD and ST muscles (P < 0.05). There were no significant differences between treatment groups in terms of meat quality parameters studied. This study confirms that maternal nutrition level during mid-gestation alters the postnatal growth and muscle fibre development of lambs.

The effect of maternal nutritional status during mid-gestation on placental characteristics in ewes

The aim of this study was to determine the effects of maternal nutritional status during mid-gestation on placental characteristics in ewes. Time of estrus of 3-5 years old Karayaka breed ewes was synchronized and mating was monitored to determine the day 0 of gestation. The ewes had similar body weights (47.8±0.7kg) and loin eye muscle values (thickness; 20.9±1.0mm and fat thickness; 4.7±0.5mm) at mating. The ewes were allocated into two treatment groups at day 30 of gestation; under-fed (UF; n=12) and well-fed (WF; n=13) groups. The ewes in UF group were fed with a diet to provide 50% of their daily requirement from day 30 to day 80 of gestation and 100% of their daily requirement during the rest of the gestation period. The ewes in WF group were fed at least 100% of their daily requirement throughout gestation. The singleton bearing ewes in the UF group had a lesser (P<0.05) placental weight (354.1 compared with 378.3g), average cotyledon weight (1.50 compared with 1.82g) and lamb birth weight (3.8 compared with 4.2kg) than singleton bearing ewes in the WF group. There were positive correlations between placental weight and lamb birth weight (r=.469; P<0.05), placental weight and average cotyledon weight (r=.695; P<0.01), average cotyledon weight and lamb birth weight (r=.742; P<0.01) and placental efficiency and cotyledon density (r=.853; P<0.01) for ewes in WF group. Additionally, the pattern of weight gain/loss was different (P<0.05) between the two groups. Ewes in UF group lost body weight progressively from day 30 of gestation until day 80. The results of present study show that under-feeding of ewes during mid-gestation may cause an insufficient placental development and hence alter fetal development resulting in a reduced birth weight from singleton pregnancies.

Estimates of (co)variance components for direct and maternal effects on birth weight of Karayaka lambs

The purpose of this study was to estimate the genetic parameters for birth weight of Karayaka lambs by separating direct genetic, maternal genetic, and maternal permanent environmental effects. Records of 1013 Karayaka lambs born between 2005 and 2010 were analyzed. Six different animal models were examined, all including direct additive genetic variance and various combinations of genetic and environmental maternal effects. The most appropriate model was chosen based on log-likelihood ratio tests. Since model 1 had the smallest likelihood value, it was chosen as the best model in this study. Depending on the model, direct heritability varied from 0.37 to 0.55 and maternal heritability ranged from 0.08 to 0.20 for birth weight.