Intelligent energy management in dairy cows

Going from the late dry period to early lactation requires an incredible adaptation of the cow’s metabolism. No period of her life is posing more physical and physiological challenges - with important consequences for her health. The energy requirement increases within days by factor 4. Energy intake via feed is not able to follow so the cow gets into a negative energy balance (NEBAL). That means she is starving. This condition can last up to 100 days. Consequently cows mobilize tissue from their muscles (protein and glucose) but most important, from the fat stores (fat). With a breeder’s view those cows are capable for high milk production by maximizing mobilization of tissue. These are the daughters of the bulls with high 100 day lactation yield. Mobilization leads to an increase in plasma fatty acids (NEFA=non esterified fatty acids) and a drop in plasma glucose levels. The liver becomes overloaded with NEFAs, liver fat concentration increases and keton bodies rise in plasma. Via a feedback mechanism keton bodies reduce feed intake. We are finding a high negative correlation between liver fat concentration and feed intake.

Many cows can’t manage the extreme changes without damage to their health. This gives rise to the typical metabolic problems and subsequent diseases: ketosis, milk fever, mastitis, laminitis, retained placenta, metritis, displaced abomasum, etc.. Adjusting nutrition during the transit time can help to alleviate these problems. Even a slight imbalance resp. a slight lack of an essential nutrient during this critical phase can put the cow into a significant health risk.

By selection and breeding, we have produced animals which have the clear target to produce as much milk as possible and not to care much for their own wellbeing. In that sense, we have changed the natural balance between the two universal principles of survival and reproduction towards lactation which is a very specific part of reproduction. That means cows have increasingly problems to maintain health and to get pregnant. We could wait until breeding surprises us with a new cow but that will take a while since milk yield and reproduction are negatively correlated and latter has a low heritability. An alternative is to help the cow redirecting her nutrient streams towards her own health. When cows were only grazing, they calved in mid spring, a time, when pasture grass provides high levels of vitamin E, beta-carotene and trans-10, cis-12 CLA. This latter compound is biologically very effective and capable to save energy due to a reduction of milk fat de-novo synthesis.

While we usually supplement our transition cow diets with vitamin E and betacarotene – in case of low levels in the forage – we forgot about the importance of CLA. In any consideration of CLA as an essential micronutrient in the dairy cow, it is important to recognize that the term CLA refers to a group of isomers rather than a single fatty acid. There is a substantial body of data reporting the physiological effects of cis-9, trans-11 CLA and trans-10, cis-12 CLA in humans, rodents, and dairy cows. Commercial supplements of CLA are produced from sunflower oil and contain both of these isomers in a 50/50%-ratio. The most researched and most active CLA- isomer in the cow is trans-10, cis-12. This compound is well known for its milk fat reducing effect, thereby reducing the energy concentration in milk and leaving nutrients and energy for the cow to redirect according to her metabolic stage. Typically a milk fat reduction in early lactation will result in higher milk yield that lasts beyond the days of supplementation. Additionally, research papers report about positive effects on plasma glucose level, the somatotropic axis, liver fat content and reproduction.

The surprising improvement in yield and reproduction is fueled by a more efficient utilization of glucose and energy. This conclusion is supported by several findings:

1. Cows – and ewes – with CLA supplementation produce milk with up to 100% more vitamin E (and A). In-vitro trials have confirmed that CLA is improving the antioxidant capacity of mammary cells, which explains the higher vitamin E levels in milk.

2. Cows with CLA supplementation have more competent granulocytes, expressed as a higher percentage of phagocyting cells.

3. Supplementing trans-10, cis-12 will save energy per liter of milk by reducing milk fat de-novo synthesis.

4. Cows with CLA better maintain their BCS after calving. They mobilize significantly less tissue mass than control cows do, although the calculation says they are on a more negative energy balance.

 

 

By slightly reducing milk fat de-novo synthesis, CLA leaves glucose and energy at the disposal of the cow and she will redirect them depending on her metabolic needs. Typically we find an improved redox status in the mammary gland and a lower mobilization of body tissue. As a result, CLA is improving performance, reproduction and health of the dairy cow.