increase, feed is more expensive. Therefore, providing too much protein – which is ultimately being excreted by the cow – is an ineffective and costly nutritional strategy.
3. Omega-3 fatty acid supplementation Supplementing dairy cow diets with omega-3 fatty acids, es- pecially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can offer an additional energy source to help miti- gate the negative energy balance common in high-yielding dairy cows. EPA and DHA can provide a highly digestible en- ergy source and are well documented to support fertility and pregnancy rates in dairy cows. An improved energy balance can also help to support lactation performance and reduce the omega-6:3 ratio. Ensuring optimum fertility is vital to the success of any dairy enterprise. Reproductive failure has been recognised as the most prevalent reason for involuntary culling globally. This is associated with significant costs in replacing these animals, as well as the consequent loss in milk production. Pregnancy rates of under 20% are all too common, whereas a target of 30–35% should be achievable. A previous study conducted by Wiltbank in 2016 demonstrated that while around 70–80% of services result in successful fertilisation of the egg, by day 28 post-insemination only 50% of cows are actually pregnant. This is reduced to only 38% by day 42, with this early embry- onic mortality being primarily due to failure of maternal rec- ognition of pregnancy. A trial was conducted by the University of California Davis in conjunction with Anpario to determine the effect of the
omega-3 fatty acids EPA and DHA on the fertility and milk quality of high-yielding dairy cows. Three hundred multipa- rous lactating dairy cows, producing more than 50kg milk/ cow/day, were assigned to one of two dietary treatments. This was either a control diet, consisting of a basal total mixed ration (TMR), or the same base diet supplemented with Op- tomega Plus, at 160g/head/day. The cows were artificially in- seminated following a double-OvSynch programme for first service and, if unsuccessful, a single-OvSync programme for second service. The cows were from a high-performing dairy herd with conception rates above 50% to first service. There- fore, no improvement was expected. However, the supple- mentation of TMR with omega-3 fatty acids EPA and DHA in- creased conception rate to second service from 39.5 to 49.1% – an increase of almost 10% points (Figure 1). The feeding of Optomega Plus in this study did not impact DMI, with intakes the same in both the control and treatment groups. Therefore, unlike some other alternative fatty acid supplements available, intakes were maintained most likely as a result of the enhanced palatability of feed supplemented with Optomega Plus. In addition, although dietary protein in- take remained the same, this study also showed that Optom- ega Plus supplementation resulted in a higher milk and pro- tein yield. Therefore nitrogen efficiency was improved by almost 2%, from 27.8% to 29.5%. This outcome, combined with the benefits seen in conception rates, is a very exciting and important result.
References are available on request. ▶DAIRY GLOBAL | Volume 7, No. 3, 2020 13
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