PSII-13 - Impact of maternal phosphorus intake on colostrum quality, calf growth, and calf immunoglobulin concentrations in primiparous beef cows

The objective of this experiment was to evaluate the effect of maternal phosphorus intake on growth and health of their calves. Treatments were 1) a free-choice mineral containing no supplemental P or 2) a free-choice mineral with 4% supplement phosphorus. Primiparous crossbred Angus beef cows (n = 36) were stratified by body weight and pregnancy status (bred by artificial insemination or natural service) then assigned to pasture groups (4 groups, 2/treatment, 9 heifers/group). These bred heifers had been receiving these same dietary treatments from 30 days after weaning until confirmation of pregnancy. Eighteen bred heifers from each treatment were selected randomly to continue into this experiment. At calving, colostrum and blood samples were collected from a subset of 12 heifers/treatment (6/group) and evaluated. Body weights and calf viability scores were obtained for all cattle. Data were analyzed using the MIXED (for continuous data) and GLIMMIX (for scoring data) procedures of SAS using group as the experimental unit. Cows grazed mixed grass pastures; monthly forage samples ranged from 0.28 to 0.36% P. There were no differences (P > 0.10) for cow body weight during gestation, calf birth weight, calf viability scores at birth, or calf weight at an average age of 21 days. There were also no differences (P > 0.10) in colostrum components (fat, protein, lactose, and IgG), or in the serum IgG or plasma mineral concentrations for both cows and calves 48 hours after parturition. All calves were sampled at approximately 21 days of age and there were no treatment differences (P > 0.10) in serum IgG concentrations. There were no benefits to supplementing gestating heifers with phosphorus when they grazed pasture with a history of fertilization with livestock manure.