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Is the thought of Calving and milk-fever cows keeping you up at night? Calving is a busy and stressful time on farm, not only for farmers but for the cows as well. The cows have the demand of pregnancy and successfully giving birth, but also producing energy dense colostrum to feed their calf. Improved nutrition through the transition period can improve animal health and welfare outcomes for your herd, but also takes some of the stress off our cows. If we can take the stress off our cows, then we can make calving less stressful for farmers and staff also.
So, what is the transition period?
The transition period is the 4-week window pre-calving to the four-week window post-calving. During this period, the cow undergoes a series of challenging metabolic changes that allow her body to adapt to the demands of calving, lactation and getting back in calf again. The transition period is also the stage of the cow’s lactation cycle when the cow is at great risks of health problems which impact on herd productivity. Around 80% of cow health problems occur within 4 weeks of calving – including milk fever (hypocalcaemia), grass tetany (hypomagnesaemia), ketosis, retained placenta, metritis, ruminal acidosis, displaced abomasum, mastitis, and lameness. Around 80% of disease costs in adult cattle occur in the first 4 weeks after calving. There is also the increased likelihood of early culling or death during this period.
Effective pre-calving transition nutrition has five key aims:
1. Meet the cow’s increasing demand for energy and protein
2. Maintain dry matter intake
3. Adapt the cow’s rumen to the post-calving diet
4. Minimise the risk of milk fever and other cow health problems
5. Minimise body condition loss and the risk of ketosis and fatty liver
If these five key aims are achieved the benefits are considerable and include:
The cow is set up for a productive lactation
Almost no clinical cases of milk fever in the herd
Very low incidence of other health problems soon after calving
Reduced death and culling rates around calving
Improved herd reproductive performance
Less time and stress spent treating sick and downer cows
Improved animal welfare
1. Meet the cows increasing need for energy and protein
In the last weeks before calving the energy demands on the cow increase rapidly. This is due to a rapidly growing foetus which requires glucose and amino acids as its fuel source and the production of colostrum at the udder. The calf has a priority demand for glucose above the cow. The calf also requires four times more glucose than she does acetate. This highlights potential problems when we are feeding cows diets high in fibre but low in fermentable carbohydrates and protein. In this situation cows are more prone to mobilising large amounts of body condition which predisposes the cows to fatty liver, ketosis, and pregnancy toxaemia.
2. Maintain dry matter intake
Close up dry cows and fresh cows are often unsettled and prone to spend less time foraging. During the final days before calving dry matter intake can drop by 30%. If we offer low energy density rations, then we may drop nutrient intake by much more than 30%. If we have low energy density in the pre-calving diet, then this may lead to mobilising large amounts of body condition. Close up dry cows also become increasingly resistant to insulin which helps them mobilise large amounts of body condition in a short amount of time. During the transition period it is the vagus nerve which is dominantly controlling dry matter intake. When large levels of fat are oxidised at the liver then this can reduce the firing rate of the vagus nerve, sending a message to the cows’ brain to reduce appetite. Cows that have better dry matter intakes have been proven to have better performance through out lactation.
3. Adapt the cow’s rumen to the post-calving diet
Over the dry period we are generally feeding diets which are less fermentable and have larger proportions of silage. Dry cow diets have lower dry matter intake levels and less total metabolizable energy than during early lactation. As a result, papillae surface area declines during the dry period (K. Dieho et al, 2016). The process restore papillae surface area in the cow can take 3-6 weeks. We also want to adapt the rumen microbes to our milking cow diet. It can take 5-7 days to adapt the rumen microbes to a new feed type. If adaptation of the rumen papillae and microbial population commences prior to calving, then we better equip the cow to be able to absorb Volatile fatty acids and therefore energy post-calving.
4. Minimise the risk of milk fever and other cow health problems.
Minimising the risk of milk fever should always be the aim of any transition diet. Although cows have plenty of calcium stored in their bones, they need at least one week to begin the mobilisation process. The onset of lactation increases the cow’s calcium requirements by 2-4 times. If the cow’s calcium demand at calving exceeds supply her blood calcium level will fall, resulting in milk fever. For every clinical case that we see there will be 8 cows that are sub-clinical. Sub-clinical milk fever is a hidden cost that creeps into dairy farm systems. It has been linked to many health conditions that result in either animal health costs, poor milk production or poor reproduction.
One way of enabling the cow to mobilise more calcium from her bone is to minimise the DCAD (dietary cation anion difference). DCAD is the difference between strong positive ions (Potassium and Sodium) and strong negative ions (Chloride and Sulphur). The easiest way to find this is by testing all the ingredients in the transition diet and send to a feed testing laboratory. By reducing the average DCAD of the diet (to negative if possible) we can reduce the risk of milk fever to cows. This is not as simple as adding anionic salts. Diets high in pasture can be very high risk for milk fever due to high levels of potassium commonly found in pasture. An integrated approach to the diet is needed to effectively reduce DCAD. DCAD levels can vary greatly. It can be dangerous to rely on book-values, so it is best to find the DCAD for your farm. Rather than trying to take a DIY approach it will be much quicker and easier to contact a properly trained ruminant nutritionist in this area. We do not have to get the diet DCAD less than zero, but every reduction helps!
5. Minimise body condition loss and the risk of ketosis and fatty liver
Pregnant cows require a great deal of ready energy in the form of glucose to maintain their developing calves. If the diet is low in glucose precursors such as readily fermentable carbohydrates and protein, then the cow will mobilise fat deposits to try and meet this need. Fat deposits are mobilised and carried to the liver in the blood, for the liver to oxidise into glucose. This is a normal process to make up the energy shortfall that invariably occurs during pregnancy, when energy demands are high. The problem occurs because a certain amount of glucose is needed by the liver to enable it to utilise the incoming fat. If the fat is coming in faster than the liver can make glucose, then ketones start to accumulate. The liver converts these accumulated ketones to fat, a condition known as fatty liver. The increased oxidation of fat at the liver sends a satiety message to the cows’ brain to reduce appetite. This reduction in dry matter intake can result in cows being in negative energy balance for prolonged periods of time, not only affecting milk production, but also reproductive outcomes also. Body condition score at calving is a major determinant of the calving to first oestrus interval, with cows in higher body condition displaying oestrus earlie (PC Garnsworthy, JH Topps, 1982). Higher body weight of cattle before calving and post calving appetite were significant factors that increased oestrus display.
How long should cows spend on the transition diet for greatest benefits?
Milk production responses of 300- 500 litres per lactation have been reported in research trials in which cows were fed well balanced transition diets pre-calving. Recent Australian research in commercial herds indicates that the production benefit obtained is greatest when a well-balanced transition diets is fed for just over 3 weeks pre- calving.). Research suggests that reproductive performance improves when a well-balanced pre-calving transition diet is fed: up to 5% higher 6-week/100-day in-calf rate and 5% lower not-in calf
rate. The longer cows spend on the transition diets pre-calving, the greater the reproductive benefit and the lower the risk of cows dying or being culled. However, because transition feeding cows for more than 24 days has potential negative effects on the risk of milk fever and does not give any additional production benefit, 3 weeks is recommended (Dairy Australia).
How much do you have to gain on your farm?
How much you potentially gain from improved transition nutrition on your farm depends on:
· Which approach to transition feeding you are willing and able to use
· Your current levels of milk fever and other cow health problems
· Your current herd production and reproductive performance
· How well you set up and implement your transition feeding program to gain the full
· potential benefit it offers
However, one thing is clear: The more that is done to help the cow successfully deal with the challenges
of calving, lactation, and mating, the greater the benefit.
So, what does the transition diet look like on farm?
Due to different breeds and sizes of cows, feeding infrastructure, and ingredients available the transition diet will look different for each farm. Simply adding anionic salts is not enough. It takes an integrated approach to ensure the cows are getting enough energy, fermentable carbohydrates, protein, macro/microminerals and vitamins as well as managing the DCAD of the diet. You are only running the diet for springer cows in the last 3 weeks pre-calving.
Ask us how we can help your cows do better and have a less stress calving!
Article Written By:
Steve McGill
BappSc (agriculture), AARNe, NZARN
Farm Consultant / Ruminant Nutritionist
References
Dairy Australia. An introduction to transition cow management.
K. Dieho, A. Bannink, I. A. L. Geurts, J. T. Schonewille, G. Gort, and J. Dijkstra. (2016). Morphological adaptation of rumen papillae during the dry period and early lactation as affected by rate of increase of concentrate allowance. Journal of Dairy Science, 99:2339–2352.
PC Garnsworthy, JH Topps. (1982). The effect of body condition of dairy cows at calving on their food intake and performance when given complete diets. Journal of Animal Science, 35 (1), 113-119.