Calf Health and Immunity.

Abstract

Suckled calves had significantly higher serum IgG 1 concentrations than mart purchased dairy calves. The marked differences in immunoglobulin levels between suckled calves and dairy calves suggest that these calves received either insufficient quality or quantity of colostral immunoglobulins. Factors affecting calf serum Ig concentrations are, Ig concentration in colostrum, colostrum intake, Ig mass, calf age at first feeding, nutrition of the dam, method of ingestion, presence of the dam, age of the dam and the calf. When suckled calves were fed a similar volume of colostrum relative to birth weight (40 ml/kg) and at the same time interval post birth, there was no significant difference across the three suckler herd progeny for IgG1, IgA and IgM and total Ig serum levels at 28 and 56 days of age. However, serum IgG2 levels were significantly lower in the Limousin x beef breed when compared with the Charolais x beef breed suckled calves at 28 days of age. Healthy calves had higher serum immunoglobulins (IgG1) than calves treated for respiratory disease, enteric disease or for both respiratory disease and enteric disease. It is well recognised that immunoglobulins are absorbed from the intestine for only a short period post birth and that efficiency of absorption is dependent on ensuring that the calf receives adequate colostrum in the immediate post-partum period. Low serum IgG1 concentrations are attributable to failures to obtain adequate colostral immunoglobulins in the period immediately following birth. The mean IgA and IgM serum levels of suckled calves in the present study were only slightly higher than dairy calves while IgG1 serum levels were almost approximately twice as high. Feeding colostrum high in Ig results in higher calf serum Ig concentrations at 48h. The low serum Ig levels reported in the present study suggest that dairy calves failed to obtain adequate transfer of colostral immunoglobulins. Calves with a lower immune status are more susceptible to neonatal infection and thus the importance of colostrum in the immediate post partum period cannot be overemphasised. Thus, the identification of calves with low levels of immunity might stimulate calf producers to ensure that calves receive adequate levels of colostral immunoglobulins. The implications of the present findings are that compared with suckled calves, dairy calves are not receiving 1). adequate quantity of colostrum 2). adequate quality of colostrum. 3). Colostrum soon enough post birth 4). or a combination of all of the previous factors. Rearing calves outdoors using calf jackets had no beneficial effect on calf performance. The incidence of respiratory disease was higher in calves reared indoor when compared with calves reared outdoor with and without jackets. There was an increased incidence of diarrhoea in calves reared outdoors irrespective of calf jacket. Lymphocytes from calves with respiratory disease manifest an impaired capability to blast in vitro. Chromium (Cr) supplementation (250 mg/kg dry matter intake) enhanced the blastogenic response in healthy calves, while, calves with respiratory had impaired blastogenic responses. Supplementation with organic Cr (250 mg/kg dry matter intake) for 63 days had no major effect on physiological parameters and had select effects on haematological parameters, namely, the % monocytes. The % monocytes were significantly higher in the standard commercial milk replacer (CMR) (Skim) Cr supplemented calves when compared with the whey based (CMR) + Soya Brand B or whey based CMR + Soya Brand C or whey based enzyme processed soya Brand C + Cr treatment groups.