44% of colostrum fed to calves on NI grassland farms is of inadequate quality.
A large scale study of colostrum management practices in grassland-based dairy systems suggests that almost half of the colostrum fed to calves is of inadequate quality.
1,239 colostrum samples from 21 commercial dairy farms across Northern Ireland were analyzed for fat, protein, lactose, and IgG concentration. A subset was analyzed for somatic cell count and total viable bacteria count The objectives of this study were to investigate colostrum feeding practices and colostrum quality on commercial grassland-based dairy farms, and to identify factors associated with colostrum quality that could help inform the development of colostrum management protocols.
Variation in Colostrum Quality
Concentration of IgG showed large variations between cows and farms (Figure 1), ranging from 1.4 to 204 mg/mL IgG.
44% of the colostrum samples contained <50 mg/mL IgG, and were therefore deemed unsatisfactory in terms of quality. Consequently, a sizable proportion of new-born calves from these herds were at increased risk of receiving colostrum of inadequate quality and experiencing failure of passive transfer (FPT).
Factors Associated with Colostrum Quality
Cows calving in the winter months produced colostrum with greater IgG concentration than cows calving in the autumn and spring months (Table 3). Cows immunized against salmonella (58.7 mg/mL) had greater IgG concentrations than nonimmunized cows (51.1 mg/mL). Previous lactation 305-d milk yield had a significant effect on colostral IgG concentration; as milk yield increased, the IgG concentration also increased.
Parity was associated with colostral IgG concentration: cows with a parity of 5+ had greater colostral IgG concentration than lower-parity animals. Colostral IgG concentration was significantly lower for samples collected later than 12 h after parturition (Table 5). Length of dry period, dry cow nutrition, estimated BW gain precalving, and season of calving had no effect on colostral IgG concentration.
Taking into account the variations in IgG concentration, it may be relevant to consider how much colostrum a calf requires to achieve apparent passive transfer (APT). In the current study, 61% of calves would have experienced FPT if fed 2 L of colostrum. On average, in the current study, calves were fed 2.9 L of colostrum for their first feed. Calves fed 2.9 L of colostrum containing at least 50 mg/mL IgG would have achieved APT, but 39% of calves would have experienced FPT if fed this volume at their first feed based on the colostrum IgG concentration. To manage this risk, feeding 4 L of colostrum would result in only 19% of calves experiencing FPT. A number of management practices can have a positive influence on the colostrum quality produced, but it is unlikely that calves from cows that produce colostrum with IgG below 20 to 29 mg/mL will achieve APT, independent of management practice.
The interval from parturition to colostrum collection was negatively associated with colostrum IgG, in agreement with previous studies (Moore et al., 2005; Morin et al., 2010; Conneely et al., 2013). Therefore, reducing the time from calving to colostrum collection is a simple way for producers to positively influence the quality of colostrum fed to their calves and reduce the risk of FPT. Colostrum feeding method has been found to affect FPT; Besser et al. (1991) reported that the highest rate of FPT occurred when the calf was left to nurse the dam (61.4%), compared with bottle-feeding (19.3%) and using an esophageal tube (10.8%). In addition, Vasseur et al. (2010) found that 22% of Holstein calves 2 to 6 h old were unable to consume 2 L of colostrum from bottle-feeding. In this study, we observed that over 25% of calves were left to suckle the dam and 17% were bottle-fed; to increase APT in calves, it may be necessary for farmers to use esophageal tubes.
This study also highlighted significant levels of bacterial contamination in colostrum, much greater than industry guidelines and an area for further investigation. Improvements should be made in colostrum feeding practices to reduce the number of calves left to suckle the dam and to feed a greater quantity of colostrum as soon as possible after birth. Because APT of immunity to the newborn is associated with the timing, volume, and quality of the colostrum offered to the calf, the findings from this study indicate the importance of measuring colostrum quality and highlight risk factors that dairy producers and advisers should consider when drawing up best practice management guidelines for colostrum management.
The study was published in the Journal of Dairy Science
Evaluation of factors associated with immunoglobulin G, fat, protein, and lactose concentrations in bovine colostrum and colostrum management practices in grassland-based dairy systems in Northern Ireland