Optimising Milk Production, Condition & Fertility
The start of the milking season is an eventful time for dairy cows. Returning from grazing, transition from a dry cow diet to a fresh cow production diet, calving and start of production are all risk factors. Feed conditions at the start of lactation are often difficult, grass quality can be low, available pasture can be low, weather can be adverse etc. In the mean time we expect our cows to produce milk, to peak at an acceptable level and to get pregnant as soon as possible after our planned Start of Mating.
Our modern dairy cows have a high genetic pressure to produce milk. Even in difficult nutritional conditions they will produce, sacrificing body fat reserves and in the end even body protein to maintain production. The only point where they will let us down is in getting pregnant! Safety systems in the hormonal household will prevent these cows to cycle and to get pregnant, in fact a natural way to survive adverse conditions.
The high number of non cycling cows at the start of the mating season in New Zealand is partly due to unbalanced rations in grass based dairy systems. Feeding ruminants is feeding rumen bugs! Most of the nutrients fed to our dairy cows are broken down in the rumen. Rumen bugs will break down carbohydrates, like plant cell walls, starch and sugars, to obtain energy. They will break down protein into smaller particles and ammonia. Rumen bugs have only one aim in life: to multiply! They will multiply if conditions are right, that is when protein particles and energy are available at the same time. The life time of a rumen bug is limited. In the end they wash out of the rumen into the intestinal tract. The high acidity in the abomasum will kill the bugs and will make their protein available for digestion in the small intestines of the cow. The protein obtained from digested rumen bugs is the most important protein source for dairy cows.
Spring grass is high in protein, but low in fibre and low in carbohydrates. A ration containing mainly grass pasture is far too rich in protein, and lacks rumen-available energy. Rumen bugs will lack energy to use all the available protein. Excess protein is broken down into ammonia. Ammonia is absorbed into the bloodstream and rebuilt into urea in the liver. Urea is excreted from the cow in her urine. The whole process of getting rid of the excess protein in fact costs energy, i.e. money! Limiting the amount of grass while providing enough rumen-available energy in the form of maize silage, molasses and/or ground barley will optimize rumen bug growth and multiplication in the rumen. These rumen bugs, once digested in the cow’s intestinal tract, will provide the protein available to the cow.
Limiting the amount of grass pasture fed to fresh cows will save pasture and will give you the chance to produce some high quality, high protein grass silage. Grass silage is needed during the dry Hawke’s Bay summers to provide enough protein when grass quality is low and available pasture is limited. Being able to feed cows properly through the summer months into the autumn pasture flush will enable you to create 300 day lactations, maintaining a persistent production.
Getting the balance right in fresh cow diets will lead to higher yearly productions, while maintaining a better body condition leading to a lower number of non cycling cows and to lower empty rates.