Effect of energy and protein nutrition in late gestation on immunoglobulin G in the colostrum of dairy cows with varying body condition scores

Abstract

An experiment considered whether nutrition of dry cows or their body condition (thin or fat) affected the concentration of immunoglobulin (Ig) G in the colostrum produced by freshly calved dairy cows. Three diets were offered during the last 3-4 weeks before expected calving date: 1) a total mixed ration (TMR) containing maize silage, barley grain, canola meal and hay, fed at 1.5% of body weight (control diet), 2) the TMR plus 4 kg of pellets (energy diet), and 3) the TMR plus 3.5 kg of soyabean meal (protein diet). On average, the thin cows were 111 kg lighter (561 v. 672 kg; P<0.05), and were 1.8 units of body condition lower (3.9 v. 5.7 units; P<0.05), than the fat cows. Colostrum yields from cows with low body condition, averaged across the first 6 milkings after calving, were 10.4, 10.0 and 11.2 kg/cow.day for the control, energy and protein diets, respectively, while equivalent yields for the cows with high body condition were 10.5, 10.6 and 11.8 kg/cow.day (P>0.05). In all treatments, IgG concentrations were highest at the first milking and diminished exponentially. There was little effect of any treatment on colostral IgG concentration or yield. The main exception was that IgG at the first milking was significantly decreased by feeding the control diet to cows with low body condition. When regression analysis was undertaken, this effect of body condition on the IgG concentration in colostrum from the first milking ([IgG]) was not significant, but those of energy (total MEI; MJ/cow.day) and protein (total CPI; kg/cow.day) intake during the last month of gestation were, as described in the following weak significant regression equation: [IgG] = 50.4 - 0.36 (±0.127) total MEI + 10.0 (±3.87) total CPI [100 r² = 11.1 (P = 0.022); r.s.d. = 11.1; c.v. = 37.4%; n = 68
This regression indicates that each additional MJ of metabolisable energy consumed by cows was associated with a reduction of 0.4 g of IgG per kg of colostrum and that each additional kg of crude protein in the diet increased IgG concentrations by 10.0 g/kg.