The genetic potential of today’s dairy cows is very high and still increasing. That’s why feed and feeding strategies are becoming more and more important. It is well known that the amount of milk produced is highly influenced by the amount and quality of the feed given to the cow. It is also possible to influence milk composition through feeding.
As the cow normally experiences a shortage of nutrients in early lactation, it is important to feed the cow a well balanced diet and maximise the dry matter intake.
An unbalanced diet increases the risk of metabolic disturbances and weight loss, which have a negative effect on milk yield. Healthy, adequately fed cows will also make the transition from dry period to peak more easily.
The cow is a ruminant with four stomachs, the largest of which is the rumen. Together with the reticulum, it has a total volume of approximately 150 to 200 litres. In this digestive system there are billions of micro-organisms. They help the cow to digest and utilise nutrients in the feed. To achieve good feed utilisation, and a high milk yield, the micro-organisms have to have optimal conditions. Feeding a cow involves feeding the bacteria in her rumen. Feeding more times a day will keep the cows active. They will be pushed to eat, drink some water, and then rest in the cubicle.
The first thing to look at is the amount of available space at the feeding table. There should be about 60 to 76 centimetres of space per cow (at least 85 centimetres in hot climates) and enough room for all the cows to come and eat at the same time. There are two main reasons for this: the most obvious reason is that cows generally like to eat all at the same time, the second reason is that most first calf heifers have different feeding habits than mature cows. Only in systems where the food is permanently available and the cows have a different rhythm (like an automatic milking system) is it possible to have less space than cows at the fence. First-calf heifers will tend to eat less at a feeding, but visit the feeding table for more frequent meals. So if space at the feeding table is limited, then the first calf heifers will be the ones who lose out.
Providing fresh air in the feeding area is very important. During hot weather (above 20ºC), fans near the feed bunk will help to decrease heat stress and keep the cows eating. Once the temperature goes above 25ºC cows will reduce feed intake. Providing fresh air gives the cow the opportunity to breathe easily and helps to keep the cow cooler. It also helps to keep flies away from the feeding area.
Positioning and barn planning
Comfort at the feeding table is another very important aspect of feed management because comfortable cows will go to the feed area more often. All feed areas should be shaded, to protect cows from the sun, rain or snow and to increase the bunk life of your fodder. During hot weather when dry matter intake often decreases, fans near feed areas will reduce heat stress and help maintain intake. One last thing you can do to improve cow comfort at the feeding table, is to place a rubber mat in the standing area by the feed bunk. This will provide a cushion for their feet and legs and allow cows to stand comfortably for longer periods of time.
Natural feeding position
Cows were designed to graze forage. For this reason, many experts recommend that cows eat in a body position similar to that when eating pasture grass. Cows eating with their heads down produce more saliva, which increases their ability to buffer the rumen from excess acidity. The feed bunk should be 10 to 15 centimetres higher than the floor where the cows are standing. Cows shouldn’t have to get down on their knees to eat, nor should they have to step up to get to the feed bunk. Cows should not be rubbing their necks on a rail while eating, so the feed fence should be high enough to allow sufficient space to eat. An option is to lean the feed fence 10 degrees towards the feed bunk, as that takes the pressure off the cow’s chest while eating. This is a very easy and comfort increasing solution, if the feed fence is not meeting today’s height standards.
Frequency of eating and fresh feedstuff
Researchers at Michigan State University found that cows housed in tied-up barns ate about 11 meals per day. Those cows that ate more total dry matter didn’t have more meals per day. Their meals were just larger. The best cows on their study ate 2.3 kilograms per meal and the worst cows on the study ate 1.7 kilograms per meal. The cows that ate more also ate faster. The average eating time was 27 minutes per meal. Five hours per day were spent eating.
The feeding behaviour of first-calf heifers is different from that of mature cows. Heifers prefer more visits to the bunk while consuming smaller meals, than their older counterparts.
To be certain you are feeding the proper amount at the bunk, be sure that there is always some of the feed left in the bunk, (the optimal amount is three to four percent), after each feeding period. Usually some forage material is less palatable, spoiled or of a poorer quality than the rest and this is what the cows will sort out and leave behind. This feed is of lower digestibility. It will reduce the cow’s feed intake and ultimately lead to less milk production. If at any time the cows are being forced to eat feed left in the bunk, they are being underfed. The best way to assess this is to check the feed bunks one hour before the next scheduled feeding. There should be a thin layer of feed remaining and it should look similar to the total mixed ration or feed being fed – not just long stems or cobs because this would be another indication that your cows would eat more if it were available.
Flat rate feeding is a feeding strategy where all cows are fed the same level of concentrates during the whole or part of the lactation period. The concentrates are restricted to a certain level while roughage is fed as often as the cows want it. The cow’s energy and nutrient demands vary depending on the stage of the lactation. Because of the fixed concentrates ratio, flat rate feeding relies on fat mobilisation. The surplus of nutrients in mid-and late-lactation is stored as body fat. The cow uses the surplus when demand is high, namely in early lactation. Fat mobilisation in early lactation can cause ketosis in high yielding cows. With flat rate feeding cows are usually underfed during early lactation and overfed during late lactation. Flat rate feeding is common in countries with extensive milk production and large areas of pasture such as New Zealand, Argentina, Ireland and Australia.
Challenge feeding/feeding to yield
While flat rate relies on fat mobilisation, challenge feeding/feeding to yield aims to supply the cow with the nutrients that are needed for the actual lactation stage. Challenge feeding/feeding to yield is common in countries with intensive milk production. The advantages are that cows can be kept in proper body condition and each cow is given a fair chance to show her production potential. The incentives for this are considerable. Every extra litre in peak lactation can result in a higher total yield of up to 200 litres of milk per lactation.
In situations where competition is expected (e.g. with limited space and food), feeding behaviour is related to cow productivity. Competition at the feeding table is highest when cows return from milking and when fresh food is offered. At these times, dominant cows will demand priority in feeding. Cows that are less dominant may be limited in their access to the feeding table at these times, forcing them to eat less or to eat at times when there is less competition at the feeding table.
The rumen check (also called hunger groove) is a way of checking food intake and the speed at which it is moving in an individual cow. Stand behind the cow to look at the cow’s left flank, to assess the rumen fill. The fill indicates the feed intake, the fermentation speed and the rate at which the feed is passing through the cow’s digestive system. The fermentation and passage speed depends on the content and properties of the feed. The latter includes fast or slowly fermentable feed, the particle size and the balance between the different feed components in the rumen.
Source: D. Zaaijer, W.D.J.Kremer, J.P.T.M. Noordhuizen (2001), in J. Hulsen, Cow Signals.
Cows prefer eating from ground level to eating from elevated bunks. The condition of the feeding surface can also affect dry matter intake. Feed bunks must have smooth surfaces. Surfaces without grooves or holes that can trap feed are easier to clean and help to minimize build up of waste feed, mould growth and odour. Avoiding muddy conditions and manure build-up on feed bunk aprons is also important. These conditions can decrease the palatability of the ration and increase the transmission of disease.
Manure scoring is a tool to help evaluate how well cow feed is being digested, whether the ration has a correct balance of nutrients (protein, fibre and carbohydrates) and if water intake is appropriate.
|Scoring of manure consistency
This manure is very liquid with the consistency of pea soup. The manure may actually “arc” from the rump of the cow. Excess protein or starch, too much mineral, or lack of fibre, can lead to this score. Excess urea in the hind gut can create an osmotic gradient drawing water into the manure. Cow with diarrhoea will be in this category.
Manure appears runny and does not form a distinct pile. It will measure less than 2.5 cm in height and splatters when it hits the ground or concrete. Cows on lush pasture will commonly have this type of manure. Low fibre or a lack of functional fibre can also lead to this manure score.
This is the optimal score! The manure has a porridge-like appearance, will stack up 4 to 5 cm, have several concentric rings, a small depression or dimple in the middle, make a plopping sound when it hits concrete floors, and it will stick to the toe of your shoe.
The manure is thicker, will stick to your shoe, and stacks up over 5 cm. Dry cows and older heifers may have this type of manure (this may reflect feeding with low quality forages and/or a shortage of protein). Adding more grain or protein can lower this manure score.
This manure appears as firm faecal balls. Feeding a straw based diet or dehydration would contribute to this score. Cows with a digestive blockage may exhibit this score.
Source: D.Zaaijer, W.D.J. Kremer and J.P.T.M Noorhuizen.
|Scoring of digestion (feeling by hand)
Manure feels as a creamy emulsion and is homogeneous. There are no visible undigested food particles.
Manure feels like a creamy emulsion and is homogeneous. A few undigested food particles are visible.
Manure doesn’t feel homogeneous. Some undigested particles are visible. After squeezing in the hand, some undigested fibres will stick to your fingers.
Bigger undigested food particles are clearly visible. A ball of undigested food will remain after squeezing the dung in your hand.
Bigger food particles are tangible in manure. Undigested components of the feed ration are clearly recognizable.