Pre- and post-weaning performance of artificially reared calves. II. The effects of milk substitute and milk substitute-whey diets on the performance of calves with particular reference to the selection of calves with improved growth potential from their blood composition a week after birth.
Sixteen Friesland bull calves were divided into two groups and raised artificially in an early weaning system. The liquid feeding of one group consisted of a commercial milk substitute and that of the other group of a 50:50 milk substitute-whey mixture. Blood samples were taken at regular intervals, starting one week after birth, and analysed for packed cell volume (PCV), blood glucose and haemoglobin (Hb); serum albumin, total protein, urea, inorganic phosphate (Pi), Ca, Mg, Na and K. The liquid portion of the diet had no significant effect on either the blood composition of the calves or on their performance (mass gain, dry matter intake and feed conversion) at the end of the experimental period (week 13). The only significant difference (P less than 0,05) between the two groups was the body mass of the calves at weaning. There were significant changes in the concentrations of most blood constituents with age (P less than 0,001 for Hb, PCV, albumin, globulin, Pi and K; P less than 0,01 for urea and Ca). A significant correlation (P less than 0,05) was also found between the calves' growth rates from 1 to 13 weeks and the concentration of globulin at one week of age. The regression of growth rate from 1 to 13 weeks with the blood constituents, globulin, Hb, PCV, Pi, Mg and Ca at one week of age accounted for 67,4% of the variance among calves. The evidence suggests that the above types of liquid feeding in an early weaning system would not significantly affect the composition of the blood of calves when sampled approximately six weeks or more after weaning, provided a predictive assessment of subsequent growth performance.
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000254:growth & development*; D008297:Male; D008892:Milk; D014886:Weaning