Managing Persistency in Milk Yield – Dairy Herd
Spring and early summer 2021 have thrown up challenges with grass availability from early April to mid-May, which in turn lead to buffer feeding in some circumstances and issues with induced phosphorous deficiency due to moisture deficit giving rise to pica.
Once peak is achieved, and remember, you get one opportunity to achieve this, then management of persistency is critical to maximizing profitability. The target here is an average of a 2% drop per week from peak, starting from that theoretical peak date of 55 DIM from the mean calving date. As one can see from table 1 for the herd the mean calving date (MCD) is 10/04/2021 but in all herds, 25-33% of the herd will calve from March onwards and will peak a month later as will be the 100-day intervals.
The month of June is critical just coming off-peak, a lot of farms can drop by 3% to 4%, higher than that 2% target. Important here is to establish production of the herd which can be achieved through milk recording and identifying the number of cows that are over the average, usually 45%-48%. These cows could be over the average by 3-4 litres/cow.
In the scenario of butterfat increasing in one collection by up to 0.2% with a corresponding drop in milk lactose of up to 0.03% corresponding to 1 litre/cow of a drop, one might not think much but it’s the heavier milkers that have probably dropped by up to 2 litres. A butterfat increase of this order will have probably come off the cow’s back as a milk lactose drop of 0.05% is very large. Lactose is an osmolyte and reflects the energy intake and digestibility of the diet, therefore, determining the milk volume, for this stage of the second 100 DIM, the lactose% should be 4.75% to 4.80%. In addition to milk persistency, the cow should be gaining liveweight and this is critical for good conception rates and herd fertility.
Managing grass quality in this period is critical with grass in its reproductive stage of growth targeting covers of 1,350 kg DM/hectare for maximum utilization and quality. Mowing down the sward in the case of covers of 1450kg DM/hectare ahead of cows to ensure a good clean up can result in drops in milk and in some cases clinical ketosis. This is due to the NDF% being around 47% versus a target of 35%-38% therefore the cow cannot consume enough and digestibility will be low.
Read more about peak milk yield; Peak Milk Yield and Breeding. Managing The Dairy Herd – Nutribio News Nutribio and follow our social media pages to keep up with updates; Nutribio Ltd.: My Company | LinkedIn , Nutribio (@NutribioLtd) / Twitter , Nutribio | Facebook