The transition period for the dairy cow; three weeks prepartum, into three weeks postpartum is the most important phase in the lactation cycle. Rightly, transition management is receiving much greater attention and more importantly so is the nutrition.
There have been several papers reviewing nutrition, with Santos (2011) and Garnsworthy (2008) leading to some interesting conclusions. They found that reduced dry matter intake (DMI) pre-partum is the cause of many metabolic disorders, causing:
- Fat mobilization – leading to fatty liver development and ketosis
- Poor immune function – which will pre-dispose the cow to metritis/mastitis post calving
- Empty rumen fill – leading to displaced abomasum
It is therefore essential that DMI pre-partum is maximised and that the feed trough is never empty for a good transition.
As important as DMI, if not more so, are the nutritional parameters of the transition diet. It is important for the diet to be balanced and not to over supply energy or crude protein. The dry cow has no requirement for a high energy diet, as this will lead to metabolic disorders i.e. ketosis, fatty liver, and excessive Body Condition Score (BCS).
Recent findings from Huan et al (2014) and Overton (2017) support feeding a low energy diet. The University of Illinois’ Dr. Gordie Jones (Golden Sands Dairy) developed the low energy/high straw “Goldilocks”diet, a controlled energy diet that is widely used across the USA and now Europe. The diet consists of straw, grass silage, maize silage, quality protein together with a high specification transition mineral.
The transition cow has an amino acid (AA) requirement, not a crude protein requirement, just as a fresh cow does. This requirement is elevated as the calving date draws closer, due to the drop in DMI and the demands of colostrum synthesis and fetal growth. The AA’s come from microbial protein synthesis and rumen undegraded AA’s from feed sources (protein supplements, forages and grain sources). These two protein sources combined form metabolizable protein (MP). It is important that quality protected protein is part of the protein supply in the transition diet, so it can be laid down as labile tissue for utilization post calving for energy to negate the energy gap. Additionally, this supply of MP will also aid production, reproduction and the immune responses post calving.
If the supply of MP is limited in the transition diet, this has been shown to have significant negative effects on the postpartum performance. Van Saun et al. (1993) fed the same diet prepartum, but with differing MP levels to two groups of cows – the higher MP level with 1200g/d of MP, and the lower MP level having 900g/d. The group fed the low MP diet prepartum consistently produced lower percentages of milk protein and, more importantly, fewer kilos of protein between 14 and 35 days in milk. Interestingly, although both groups were fed the same basic diet, cows fed the low MP diet lost more body condition in the first two weeks. Additionally, the reproductive parameters for the two groups showed a distinct difference.
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To date we have not adjusted our transition diet parameters for MP supply and may be unintentionally underfeeding MP. No account is taken for the heavier cow with twins, reduction in feed intake, or the higher birth weight calf. These factors increase the requirement for MP and AA’s. The suggestion is to formulate diets to achieve an MP intake of 1200g/d for the mature Holsteins and 1300g/d for Holstein heifers. If applied, we may actually be meeting the requirements for MP and having a positive effect on postpartum performance.
Dairy Technical Specialist
m: 07454 015610