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Imagine a dairy cow that gave 15,000 litres (33,000 lbs) of high quality milk year, after year, after year, at a high level of efficiency; a cow whose milk had health benefits for the consumer; a cow that got pregnant when you wanted her to; a cow that was highly resistant to infections such as mastitis and whose milk had a consistently low somatic cell count; a cow that never suffered from acidosis and a cow that was never lame. Now imagine a herd of such cows and imagine how profitable it would be!
The reality is, unfortunately, somewhat different. In the United Kingdom, over the last 10 years, the average yield of Holstein cows has increased by nearly 20%, but this has been associated with a 9% fall in butterfat percentage, a 27% reduction in conception rate, an increase in mastitis and general health problems and the loss of nearly 1 lactation in longevity. Some veterinary surgeons believe that nearly all early lactation cows in the UK suffer from subclinical acidosis.
Why is this? Some people see a causal relationship between these issues: ‘High yields cause disease’ or‘High yielding cows are infertile’, but that is confusing a correlation with a cause. I accept that there is a strong correlation between high yield, mastitis and poor conception rates, but I do not believe that high yields cause these problems.
The science of genetics may hold some of the answers; and breeders in some areas are now selecting for disease resistance and longevity. The science of nutrition may be equally helpful, by resolving trace mineral nutrition problems and examining ways of maintaining rumen stability, and we certainly need to re-examine management strategies for the modern high-yielding cow. None of these, however, will alone provide the solution. A holistic re-appraisal of dairy cow management is required – we need to re-create our view of the dairy cow.
Because we have not followed a holistic approach, developments in the different areas have not kept pace with each other. Management has certainly not kept up with genetics. Essentially we have bred racehorses but persist in management techniques more appropriate to ponies. It is a bit like breeding a horse and training it for flat races….and then entering it for the Grand National and wondering why it falls at the first fence!
We need to address a number of problem areas in dairy management:

• The obsession with yield as the goal rather than profitability, in breeding as well as feeding.
• Using margin over feed as a target rather than net profit.
• Dependence on ration formulation computer programs that are really nutritional models dealing with one cow that is assumed to have fixed requirements, rather than the reality of having a group of cows that respond to how we feed them.
• Forgetting that the cow is a ruminant.
• A focus on energy density rather than dry matter intake.
• Reliance on out-of-date mineral allowances rather than absorbed nutrient requirements.
• Management systems that have been developed for the convenience of human beings at the expense of the cow.

You might be able to add to this list. In fact, each of these points is a subject for a paper on its own, but the point, however, is that these issues must be dealt with in a co-ordinated fashion. A holistic approach is needed; and in order to do this, we need a framework: a way of thinking about dairy cows that works for both the cow and the dairy manager.


A new look at the dairy cow cycle

THE CONVENTIONAL VIEW: THE COW’S YEAR ON OUR TERMS

A good starting point is a paradigm shift in the way we view the cow ‘year’. Figure 1 illustrates the conventional textbook view. It does, at least, recognise that the cow’s year is cyclical and implies that problems in one time period may well have been caused earlier in the cycle. Another way of looking at this is: if you mistreat a cow in one period, she will probably make you pay for it later on. For example, the cause of poor breeding performance 60-80 days into the lactation is often related to incorrect feeding and management during the dry period.



The problem with this conventional view is that firstly, the cycle is presumed to be one of 365 days, and secondly, that periods of 100 days mean very little to the cow!
We need to start viewing the cow cycle from the cow’s point of view. If we want high genetic merit cows to perform to potential and consequently to deliver the full economic benefits of such ‘improved’ breeding, we must adapt our management of the cycle to work with the cow, not to arbitrary time divisions that suit our convenience.
Clearly any management system must be practical: we must always compromise when fitting the ideal for one cow to a herd, and to the facilities available. What I am proposing could be applied on most commercial farms as it is essentially an approach or perspective, rather than a system. It is the attitude of mind that focusses on understanding what a cow wants to achieve and helping her achieve it, rather than forcing her to fit outdated systems.


THE COW CYCLE FROM HER POINT OF VIEW

The first issue I have with the traditional cycle is “Why are we fixated on 365 days?” Why is a calving interval of this length perceived as a good thing? This, I believe, goes back to when we had cows that followed a classic lactation curve, dwindling to very low yields (or drying themselves off) at 300 days. Any extension of the calving interval of these cows meant extending the days dry and was expensive in terms of lost annual yield. The modern Holstein has a flatter, more persistent lactation curve. At 300 days she may still be yielding 30 litres (66 lbs) or more. Why do we dry cows off giving this much milk (leaving aside that this could be perceived as a welfare issue)?
I am not arguing for extending the lactation to 18 months; the benefits of this have not been proven, but merely that we should take the emphasis away from calving interval as an objective and certainly as an indicator of herd fertility. This allows us to delay the onset of breeding until the cow has moved out of the extremes of negative energy balance exhibited by high yielding Holsteins into a period when we are more likely to be successful. Letting the calving interval increase to 400 – 420 days is not a problem unless the days dry increases.
Figure 2 illustrates the second limitation of the traditionally-defined 365 day cycle. Cows are considered to be ‘in early lactation’ for 100 days, then we change the feeding rate and move them into the mid-lactation group. Unfortunately, the cow does not realise that she is supposed to have made a physiological change at 100 days after calving.





CONCEPTION MANAGEMENT

For a cow to calve at 365 days, she must be successfully inseminated at 80 days. Embryo implantation usually occurs 20-50 days after this and its success will be markedly reduced by stress, either nutritional or managerial. Yet this particularly sensitive period for the cow coincides with the time when the traditional cycle would have us change her feeding and management. I suggest that we replace the term ‘early lactation’ with ‘conception management’, because in the natural course of events, once the cow has completed the transition from pregnancy to lactation, conception will be her primary objective. This period should last for at least 130 days, or in practice until a successful pregnancy diagnosis, and will coincide more nearly with the hormonal status of the cow (Figure 3).




During the conception period: management for intake

The energy status of the cow during the conception period is well-known to be critical, but this has led in many cases to an overemphasis on the energy density of the diet at the expense of rumen function and hence dry matter intake. The only way to increase diet energy density is to increase the starch and/or the fat content at the expense of fibre. However the point at which the balance of the diet is upset is quickly reached and rumen function can become impaired. The typical pattern is illustrated in Figure 4.



It is critical to keep in mind that a cow is a ruminant. Optimum health and production are only achieved using diets formulated for optimum rumen function. It is in this nutritional context that the rumen modifiers such as Yea-Sacc® have an important role, because it works to remove one of the practical obstacles to dry matter intake (ruminal forage degradation rate) to achieve the best energy status of the cow. Other obstacles include water intake and feed presentation, palatability and management –again, subjects worthy of papers on their own.


BODY RESERVE MANAGEMENT

Management for intake during the conception period is highly dependent on what happened late in the previous lactation. Cows must be dried off at the optimum condition score for calving (3.0-3.5) because we should not attempt to change condition when they are dry.
Gaining condition during this period means‘overfeeding’, and will simply result in any extra feed being partitioned to the calf or the udder. ‘Underfeeding’ to lose condition is equally mistaken during this critical period. In any case, there are more important objectives during this period.
Making sure cows are in the right body condition at drying off means checking condition score 100 days before drying off such that needed changes can be achieved during this last period of the lactation - which is the next paradigm shift. Rather than using the term‘late lactation’, which implies ‘unimportant’, and seems to mean that we can ignore her, I would prefer the term‘body reserve management’. This term suggests we have something to accomplish during this period. However, it is not just condition score we must consider. It is also important to think in terms of managing her protein and mineral reserves.
The ‘dry period’ also needs a new approach. ‘Dry’ cows are all too often an area of management neglect.
They are put to one side and ignored until just before calving and yet, if we want to achieve high energy status post-calving through high intakes, this is the time to prepare the rumen for a rapid response to the actation diet. There are two stages to this, physical preparation and preparation of the ruminal microbes.


Physical preparation

At the point of calving, a cow contains a 45+ kg calf, plus the placenta and fluids, which crowd the rumen and compress it. Muscle tone can be lost since normal ruminal movement is reduced. At calving, there is once again (and suddenly) space for a full rumen. To avoid a displaced abomasum and to ensure a rapid rise in intake, the rumen must immediately fill that space and be ready to go. The way to make sure this happens smoothly is to keep the rumen working in late gestation: keep it full and physically in tone with diets based on high fibre forages, chopped no shorter than 5 cm. The rest of the diet can be made up with whatever feeds are available, as long as the total ration is balanced correctly for all nutrients including the minerals and vitamins.


Preparing the ruminal microbes

The last part of the cycle, the pre-calving transition or‘close up’ period, involves training the rumen microbes for the task ahead. The population of microbes in the rumen takes 12-14 days to adjust to major changes, therefore introduction of a controlled amount of the lactation ration into the diet is needed for the last 2-3 weeks before calving. This another point where Yea- Sacc® is of value as a rumen modifier for its ability to reduce stress on the rumen during periods of dietary change.
During this period, particular attention should be paid to supporting the immune function of the cow. Trace elements should be correctly balanced throughout the cycle but the form and availability are especially important during this critical time. The management of the cow pre-calving can make a difference of ±3.5 kg dry matter intake immediately post-calving! Done correctly, intake and energy status will surge and a solid foundation will be established for the stresses ahead.


‘TRANSITION’ vs ‘PRE/POST-PARTUM’ COW

I use the word ‘transition’ instead of ‘calving’ advisedly. The actual act of calving that we tend to focus on is merely an uncomfortable event in a process that encompasses the period 2-3 weeks either side of that event. Transition is a critical period, and some dairy farmers are now managing these cows separately. This is not always practical, but we can take steps to make it as successful as possible. There is a case to be made for treating the first 2-3 weeks of lactation as an early lactation transition group. Moving recently-calved cows into a separate loosehoused area provides an opportunity for close observation during recovery, however this may not be possible on many farms.


Conclusions

Figure 5 shows the proposed new way of looking at the cow cycle - a perspective from the cow’s point of view. This approach takes a holistic view of the cycle, with the cow’s needs foremost at all times and provides framework for re-thinking dairy cow management.

BRUCE WOODACRE
Consulting Nutritionist, Woodbridge, Suffolk, UK

Author: BRUCE WOODACRE - Alltech Inc.

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09/22/2006

Jenny Trigwell Dairy Farmer WA - Australia

Our system is more closely aligned with your propsal rather than the traditional cow cycle. We have delayed mating too soon and average calving interval is out to 400 - 420 days. We find this boosts a cows fat and protein production yield over a lactation. In late lactation they are often returning similar kg of milk solids to cows more recently calved and doing it with less stress on their bodies! The cows are in very healthy condition when dried off and do not seem to need a 60 day dry period. They can calve back in 5 or 6 weeks and not miss a beat in the next lactation. They generally get lead feed for 2 weeks before calving, depending on whether they will eat it as they are on pasture. Answer Checked by Engormix.com