The risks of disease and metabolic issues are greatest during the transition period (3-4 weeks either side of calving), which is dominated by a series of adaptations as cows move from pregnancy to lactation. As much as 80% of all health issues related to this period.
Establishing successful lactations requires an integrated transition management and feeding approach to: reduce ruminal disruption, minimise macro and micro mineral deficiencies, minimise fat mobilisation disorders, avoid immune suppression, and maintain fertility.
Maintaining good rumen function requires gradual diet changes, as rumen microbes take 5-10 days and rumen papillae 4-6 weeks to adapt to higher energy feeds, required to compensate for decreases in feed intake while nutrient requirements increase.
Nutrient supply issues around calving may lead to higher empty rates, due to development of small follicles, which take 60-80 days to mature, producing small oocytes (eggs) and corpora lutea, that may not be robust enough to maintain pregnancy. Failure to conceive early and maintain pregnancy is crucial to maintain a tight calving pattern without the option of inductions.
Insulin production declines as does sensitivity around calving, to maintain constant blood glucose levels despite declining feed intake, which may lead to excessive fat mobilisation, fatty liver and ketosis. Organic chromium helps increase insulin sensitivity, and protected long chain fats can be fed during this preiod, as they are transpotred to the tissues and mammary gland, so sparing fat processing by the liver. Rumen protected choline has also been demonstrated to speed up the breakdown of fats by the liver, thus helping to tackle ketosis.
Calcium requirements increase rapidly with colostrum and milk production, such that dietary intakes are insufficient on their own, necessitating mobilisation from the skeleton. Inadequate mobilisation responses result in clinical and sub-clinical milk fever, rendering cows more susceptible to disease and additional metabolic issues. Supplements containing magnesium and vitamin D assist with calcium mobilisation. Calcium supplementation is also necessary in many cases. Certain trace minerals are important for supporting immune function, particularly selenium in conjuction with vitamin E, which will be especially important this year after the worst facial eczema season in recent years.
Calculations based on current milk prices indicate cost benefits of at least 2:1 with sound transition management and feeding incorporating comprehensive transition supplements.
As featured in NZ Dairy Farmer