Effect of different degraded protein balances (OEB) on the performance of beef bulls and on digestibility and rumen fermentation in sheep

A total of 125 non-double-muscled Belgian Blue finishing bulls (liveweight range 375-620 kg) were used to investigate the effect of different levels of degraded protein balance in the rumen (OEB) -2, -7, -16 and -22 g/kg DM on animal performance, with the dietary content of true protein digested in the small intestine (DVE) fixed at 80 g/kg. Lower OEB levels significantly reduced daily liveweight gain from 1.57 to 1.39 kg during the first 84 days of the experiment, but not during the subsequent part. For the whole experiment, daily liveweight gain decreased from 1.40 to 1.32 kg but the difference was not significant. Intake of DM, DVE and NE for finishing was not modified by OEB level, while CP intake was reduced and OEB deficit was increased. An OEB level of -22 g/kg DM resulted in a significantly unfavourable conversion of DM and NE during the initial months (11.3 and 11.5% compared with OEB = -2 g/kg DM, respectively). For the total period the conversion of DM and NE was still less favourable, but the differences were not significant. There was a nominal decrease in cold carcass weight and dressing percentage when OEB level decreased, but the effect was not significant. The effect of different OEB levels on digestibility and rumen fermentation was investigated in a separate experiment with wethers. Apparent protein digestibility was reduced from 74.2 to 68.9% when OEB level decreased. Rumen pH and concentrations and molar percentages of volatile fatty acids were not altered by OEB level. Ammonia concentration was only reduced by a lower OEB level at 7 h after feeding. Because of a nominal reduction in daily liveweight gain, feed efficiency, carcass weight, dressing percentage and carcass conformation with decreasing OEB level, it is advisable not to feed less than -16 g OEB/kg DM in diets with 80 g DVE/kg DM to Belgian Blue non-double-muscled finishing bulls from 375 kg onwards. This tolerable OEB deficit is larger than proposed to avoid protein overfeeding

Effect of beta-adrenergic agonists in animal production and their mode of action

International audienc

Optimum growth rate of Belgian Blue double-muscled replacement heifers

Belgian Blue double-muscled (BBDM) heifers (n = 341) were used to investigate the effect of body weight (BW) at first calving at an age of two years (BWC). Females with a birth weight (BWB

Plasma T3 and T4 concentrations in newborn calves: influence of type of delivery and breed.

AIM OF THE STUDY In the neonatal adaptation to the extra-uterine life, thyroid hormones play an important role in the process of growth, energy metabolism and thermogenesis. Thyroid hormones profiles were described in newborn calves from different breeds (1), while the influence of gender, birth weight and type of delivery is still unclear. The aim of the study was to compare T3 and T4 plasma concentrations in Holstein-Friesian newborn calves born by vaginal delivery and Belgian Blue born by caesarean section. MATERIALS AND METHODS The study was conducted on 12 Holstein-Friesian calves born by vaginal delivery (VD) and on 12 Belgian Blue calves born by caesarean section (CS). Calves gender, body weight and viability were recorded immediately after birth. Blood samples were collected from jugular vein at 10 and 20 minutes (m), at 6 and 24 hours (h) and at 7 and 14 days (d) of age and plasma stored for T3 and T4 analysis by RIA. The ANCOVA for repeated measures test was used to assess the effect of gender and birth weight on T3 and T4 plasma levels profiles within each group. One-way ANOVA was used to evaluate possible differences in T3 and T4 levels between the two groups in each sampling time (p<0.05). RESULTS All newborn calves were mature and viable. Mean body weight was 34\ub14.2 Kg for VD (5 females and 7 males) and 53\ub17.7 Kg for CS group, respectively (5 females and 7 males). Means \ub1 SD of T3 and T4 plasma concentrations in the two groups of calves are reported in table 1. CONCLUSIONS In both groups the T3 and T4 profiles showed an increasing trend from birth to 6 hours of age, followed by a decrease to 14 days of age, as previously reported (1). According to statistic results, T3 and T4 plasma levels were not affected by gender and by birth weight. Statistics evidenced higher T3 and T4 concentrations in the CS calves early after birth, possibly due to the faster process of birth that may result in an immature T4 deiodination system in Blue Belgian calves. Higher plasma levels of both hormones were also detected in the CS calves at 7 and 14 days of age; differences in nutrition or in body weight gain could be responsible for these differences. Unfortunately the association between different type of delivery and different breed within each group does not allow to clarify the real effect of these variables on T3 and T4 plasma levels in newborn calves. REFERENCES 1) Davicco et al, 1982 Reprod Nutr Dev 22, 355-36