An increasing amount of time and resources are being invested in calves, as farmers recognise their importance in future-proofing their dairy herds. Colostrum plays a vital role in lifetime health and performance: a golden bullet to prevent problems before they begin! There have been huge improvements in how and when colostrum is fed, but are we doing enough to improve the value of the colostrum itself?
Vets often get asked about factors causing low colostrum yield and quality, both of which can be frustrating problems to deal with. A study published by Cornell University in 2021 followed 18,000 dairy cows to calving and monitored a range of factors which could affect their colostrum quality and/or volume. The key findings are discussed below, relating to the cow, her environment, and her diet during the dry period.
Cow Factors
• Parity. Colostrum quality (Brix %) was higher in older cows. However, heifers still produced high quality colostrum, 76% produced colostrum with Brix value greater than 22%. Second lactation cows produced the greatest colostrum volume.
• Calf viability. Cows delivering live calves had an increased colostrum yield.
• Calf sex/twinning. Cows that had either a male calf or twins had greater colostrum yield.
• Dry period length. Cows with longer dry periods (60 days versus 30-40 days) had an increased colostrum yield, but no difference in quality. A dry period greater than 67 days was associated with increased quality, and 0 days saw a significant drop in quality.
Environmental Factors
• Season. Cows which calved in the summer months (May/June/July) had an increased colostrum yield, but slightly lower quality.
• Temperature Humidity Index (THI). An increased THI was associated with an increased yield and reduced quality in this study, a similar pattern to the seasonality.
• Stocking density. A higher stocking density was associated with reduced quality, but not a reduced yield.
• Time to harvest. Colostrum which was collected more than seven hours after calving showed a significant yield and quality reduction.
• Light. Increased light intensity was associated with increased colostrum yield in multiparous cows.
Nutritional Factors
• Days on close-up dry cow diet. This study found no association with colostrum yield or quality. However, previous work found a reduction in yield when cows were on close-up diets for 10 days compared to 21 days.
• Energy density. Increasing the energy density of the diet to 150% in the four weeks pre-calving reduced colostrum quality.
• Crude Protein. Diets with 13.6-15.5% protein were optimal for colostrum yield.
This was one of the largest studies ever done looking at factors affecting colostrum volume and yield, and by looking closer at some of the factors above on your farm you could improve your colostrum harvest. Measuring colostrum success Once you’ve cracked the above and maximised colostrum quality and volume, the success of your colostrum protocols can be assessed by blood sampling calves to measure serum total protein. The aim is for as many antibodies from the dam to pass from the colostrum into the bloodstream of the calf, which protects the calf against disease until the calf has developed its own immune system. Many factors affect this transfer, including colostrum cleanliness, method of feeding and timing of feeding, but we’ll have to save those for another time!
Targets for serum total proteins are shown in the table below. The 2021 Cornell study found that calves in the fair and poor category were 5% and 10% more likely to die. Calves in the excellent category were less likely to develop disease.
Thank you to Jenny Bellini of LLM Farm Vets.
