Impact of α-amylase supplementation on energy balance and performance of high-yielding dairy cows on moderate starch feeding.

In dairy cows, exogenous α-amylase is suggested to improve starch utilization and positively affect performance and health traits linked to energy balance and fertility. In a 1-year feeding experiment, 421 cows were orally supplemented with α-amylase (treatment: 12.5 g/kg dry matter (DM) addition rate to a concentrated feed) or non-supplemented (control) on the basis of an ad libitum total mixed ration (TMR). Every cow was allocated to a high- (≥32 kg milk/day) or late-lactation group (<32 kg milk/day), in which the TMR starch content was 220 ± 20.8 g/kg DM and 183 ± 24.8 g/kg DM, respectively. The energetic effect of α-amylase supplementation seemed to be exclusively related to the high-lactation stage (5-100 days in milk) in primiparous cows, where the daily milk yield was 32 ± 0.49 versus 31 ± 0.50 kg per cow in the treatment versus control group (P < 0.05). The pluriparous cows did not benefit from the supplementation that way. In neither primiparous nor pluriparous cows, was the milk composition, the fat-to-protein ratio, the somatic cell score, the backfat thickness, serum total bilirubin, ß-hydroxybutyrate and the fertility found to be systematically affected by α-amylase supplementation.

Effects of 25-hydroxy-cholecalciferol on the development of osteochondrosis in swine.

The principal objective of this experiment was to evaluate the effect of 25-hydroxy-cholecalciferol (25-OH-D3 ) on the development of osteochondrosis in 6- to 110-kg castrated male pigs. The growth rate and serum calcium and inorganic phosphate levels neither increased nor decreased in response to supplementation of 25-OH-D3 . However, supplemental 25-OH-D3 significantly increased serum levels of 25-OH-D3 and 1α,25-hydroxy-cholecalciferol without any influence on bone mineral density. The 25-OH-D3 -treated group had significant (P < 0.05) reduced incidence of osteochondrotic lesions compared to the control group as evidenced by macroscopically examining the articular cartilage of the distal humerus (32.4% vs. 59.3%) and distal femur (47.1% vs. 87.5%). Likewise, supplemental 25-OH-D3 significantly reduced osteochondrotic lesions over the control when histologically examining humerus (20.6% vs. 43.8%) and femur (52.9% vs. 87.5%). The results of this experiment suggested that 25-OH-D3 supplementation in pig diets had a tendency to promote normal endochondral ossification, inhibit osteochondrosis progression and possibly regenerate destroyed cartilage tissue.