It is well noted that herd fertility significantly affects dairy herd profitability. Regrettably, on recent farms visits, there was evidence that the fertility of dairy cows had significantly reduced, with poor scanning rates observed.
Extended calving interval, increased culling rate, increased veterinary costs, low milk production, reduced subsequent fertility in next lactation are all real issues on many dairy farms. Infertility is a big challenge across dairy farms and farmers need to give due consideration to the main factors that affect fertility in order to improve the situation.
Dry Matter Intake and BCS
It is important to monitor the dry matter intake of cows in all stages of lactation so cows don’t suffer from a negative energy balance (NEB) particularly in early lactation. High dry matter intake and an increased ratio of sugar based feed based ingredients (beet pulp) are associated with good responses to reproductive performance. It is important to note that as the cow approaches calving she endures a reduced intake of between 25-40%. Therefore it is important to offer pre-calving cows a higher energy density diet three weeks from calving.
The hormonal changes prior to calving affect appetite and thereby reduce feed intake shortly before calving. The decrease in feed intake combined with the initiation of lactation and production of colostrum starts a period of NEB. This period must be minimised to offset the degree of mobilisation. Metabolically the cow responds releasing non esterified free fatty acids and ketones from the adipose tissue of which alters normal energy metabolism in the liver. These changes will affect ovarian function and will interfere with follicle development and maintenance of pregnancy.
The first three weeks following calving will provide the biggest challenge for dairy cows. Focus must be on reducing the degree of NEB as already outlined. I advise where possible to place cows in a separate area in the seven to ten days approaching calving and offer them a high energy dense diet. This will be important to encourage a smooth transition from non-lactating to lactating. However, ensure that changes in the diet are done so in a subtle way to avoid an oversupply of starch in the rumen. The rumen microbes need time to adapt to a change in the diet and if it is not balanced, rumen acidosis maybe prevalent, thereby also affecting reproductive performance.
Balancing the Diet
In terms of diet it is important that sufficient energy is provided but just the correct amount matched to the milk yield and genetics of the specific cow. An imbalance of energy or too much protein will have a negative impact on reproductive performance. An excessive amount of rumen degradable protein delays first ovulation or oestrus, thus a reduced conception rate to first service. The cow will have to mobilise excessive protein thereby using up energy in disposing excessive protein. If cows are already in NEB the problem is exacerbated with more ammonia and urea is produced thereby having negative effects on oocyte and embryo development. Altered pH is the biggest challenge in dairy diets following calving as acidosis is never too far away.
Appropriate Mineral Supplementation
It is important that sufficient minerals are offered six to eight weeks prior to calving together with a post calving mineral after calving. Pay particular attention to key trace elements to include magnesium, phosphorus, sodium, iodine and selenium. Don’t forget about vitamins as it is very important to have elevated levels of vitamin E to boost immunity and vitamin A and D for release of calcium.
In summary dry matter intake, protein and energy requirement together with mineral balance will be crucial to the reproductive performance, whilst the key will be to balance the diet to the type of cow you have on each specific farm. In Connolly’s RED MILLS we have tailored feeds to offset some of the associated problems I have mentioned.
For further advice on dealing with fertility problems in the herd, be sure to contact one of the Connolly’s RED MILLS nutrition team.
- dry matter