G.D. Marx

The effect of dietary energy concentration on calf performance

Abstract At three locations, 120 calves were fed a high fat milk replacer at 10% of birth weight from d 5 through 13. On d 14, calves were assigned randomly within sex and date of birth to a 2 × 2 factorial arrangement of treatments. Treatments were (on a DM basis) high fat milk replacer (21.6%) and high fat starter (7.3%), high fat milk replacer (21.6%) and low fat starter (3.7%), low fat milk replacer (15.6%) and high fat starter (7.3%), and low fat milk replacer (15.6%) and low fat starter (3.7%). Milk replacer was fed at 8% of birth weight/d from d 14 to 35 and at 4% of birth weight/d from d 36 to 42. High fat replacer depressed DMI before and after weaning. High fat starter depressed DMI after weaning. Before weaning, calves gained more BW when fed low fat replacer. Calves fed low fat starter gained more BW after weaning. On d 56, BW were highest for calves fed low fat replacer and starter and lowest for those fed high fat replacer and starter. Growth or health of calves was not improved by fat addition to the diet.

Effect of trace mineral source on reproduction and milk production in Holstein cows

ABSTRACT A lactation study was conducted to evaluate the effect of increasing the proportion of inorganic versus organic trace minerals (polysaccharides and amino-acid chelates) on reproductive performance and milk production of multiparous and primiparous Holstein cows. Trace minerals evaluated were copper (Cu), manganese (Mn), and zinc (Zn). All minerals were supplemented to meet the NRC (1989) recommended level (10, 40, and 40 mg/kg of Cu, Mn, and Zn, respectively) in diet DM. A total of 101 cows were randomly assigned by expected calving date to 1 of 4 trace mineral treatments: 1) 100% from inorganic sulfate (SULF); 2) 67% SULF:33% polysaccharide complex (SULF-POLY); 3) 67% SULF:33% specific amino-acid complex (SULF-AA); and 4) 100% polysaccharide complex (POLY). Treatments were implemented the day of calving. Number of days open was reduced (P