Science articles

Why milk replacer for rearing calves? Paweł Górka, PhD

Department of Animal Nutrition and Dietetics University of Agriculture in Cracow, Poland

Rearing healthy and well growing calves is one of the greatest challenges for modern dairy and meat producers. This, apparently short and lasting just 2 to 3 months period of cow’s life  is crucial for farmers’ income. First weeks of life are a time of intensive development of a young organism, particularly its organs crucial for future milk yield and growth of muscle tissue, such as gastrointestinal tract, liver or mammary gland. What has to be emphasized is that any disturbance in the growth of an organism at this early stage of life ( caused by f.ex. diarrhea) cannot be compensated at a later stage. As a result, it inevitably leads to less effective production results from the problem animals as well as their shorter lifespan. Ultimately, poor rearing performance of calves is the reason  for substantial financial loss of a farm.
It is estimated that every sickness of a calf within the first weeks of life may reduce milk yield of a future cow from 200 to as many as 1000 liters in each lactation. On the other hand, each increase of body mass during this critical period of life by 1 gram/day translates into a higher milk yield by as many as 4 liters per each day of lactation. Cited values allow to picture the correlation between the first weeks of the animals’ lives and their later productivity.

The emphasis on the liquid feed

Feeding is one of the most essential factors influencing calves health and development within the first weeks of life. The period of feeding liquid feed, such as milk or a milk replacer, which is the main source of nutrients by the time a calf starts taking in solid feed, is particularly important to neonatal calves. Thus, every breeder faces a major decision of selecting the liquid feed type for the young animals in the first weeks of their lives.

In this area, a breeder may base the feeding on either milk or a calf milk replacer. Regardless of the final decision, it should be proceeded by a thorough analysis of advantages and disadvantages of each solution. The analysis should consider:

  • Impact on health and body mass gains of calves
  • Impact on future milk yield
  • Repeatability of breeding results
  • Breeding cost
  • Convenience of use

A good quality calf milk replacer

A wide range of breeders use quality milk replacers as basis for rearing calves. Calf milk replacers may be introduced to nutrition immediately after colostrum and a high quality of their components accounts for their good bioavailability.

The fact that a milk replacer is  free from food-borne pathogens significantly reduces the risk of spreading diseases. Reducing the risk of deaths of young animals should become one of main targets for farmers as they cause huge financial losses.

Apart from the abovementioned advantages one of the greatest benefits of calf milk replacers is their stable composition. Any variation in the composition of liquid feed may be a source of a potential stress to a calf , which may result in greater susceptibility to illnesses and reduced body mass gains. Feeding calf milk replacers allow to sustain high repeatability of the composition of the feedingstuff, which has a positive effect on repeated breeding results. Healthy and well growing calves are likely to take in solid feed, which helps to reach big mass gains and enables to achieve the demanded doubling of the body mass by the 8th week of life. It is worth pointing out that the chemical composition of the top quality milk replacers currently available on the market (high in  proteins and energy) allows to maximize the growth of the musculoskeletal tissue avoiding excessive fattening, which helps to reach high milk yields from dairy cows and  higher carcass weight of meat breed calves.

An important advantage of feeding calves milk replacers is the independence from use of     milk, especially valuable in the case of dairy farms, and usually inevitable in the case of farms  engaged in fattening male animals. Clearly, feeding calves replacer is also easier to organize  in practice than feeding milk.

 

It has to be emphasized that the abovementioned advantages of calf milk replacer use are true exclusively for top quality products, such as milk replacers which contain milk-derived products characterized by high digestibility. The contents of protein, fat, vitamins and minerals of the products is also crucial for the success in calf rearing. Any saving on these crucial sources of nutrients for calves in their first weeks of life does not serve well the prospective production efficiency.

Pros of using milk replacers

  • microbiological purity
  • lower probability of spreading diseases in herd
  • constant, unchanging composition of liquid feed
  • high body mass gains
  • convenience of use
  • low cost
  • independence on using milk

Cons of using milk replacers

  • poor results of rearing in case of using low quality milk replacers

For and against milk

Feeding whole milk to calves may seem the most logical choice. The nutrient produced by the mother is potentially the best one to meet calf’s nutritional needs. However, the very fact that the whole milk is the most natural food to a calf does not make it ideal feed. Since practical feeding conditions are very different from the natural ones , the liquid feed has to jointly fulfill at least several conditions for successful rearing results. The conditions include:

  • high digestibility of nutrients
  • microbiological purity
  • constant, unchanging composition

Something we must not forget is the purchase cost of feed, which determines the final profitability of production to a great extent.

Although the whole milk fulfills the first criterion listed ( nutrients included in milk are very well digested by a calf) , the fulfillment of the remaining criteria turns out to be hard in practice. As a result, feeding whole milk to calves does not often come with desired effects.

The biggest disadvantage of whole-milk calf-feeding is the possible presence of pathogenic bacteria, fungi or protozoa. Whole milk may be the source of contamination with paratuberkulosis. The very fast pace of  Escherichia coli multiplication in milk may constitute a great problem from the practical viewpoint, especially that the bacteria is the main source of diarrhea in calves. To eliminate potentially dangerous situations, the whole milk should be fed to a calf as soon after milking as possible or stored refrigerated (4°C) before feeding. This consumes great amount of time and resources ( specialist equipment like freezer and heater) and may create errors while preparing the feed.

Moreover, feeding calves with the whole milk alone require supplementation of the diet with A, D3, E, B1 vitamins, selenium, iron, magnessium and copper as their levels in milk are low and vary. Besides, the contents of milk may significantly change from day to day, depending on the actual day of lactation or type of feed fed to dairy cows from which the milk is obtained. In this context, the amount of protein or energy intake may vary on a daily basis. As a result, body mass gains of animals may dramatically vary, which leads to major differences upon inseminations or sales for slaughter as well as financial losses.

It is worth to know that in nature a calf being with a cow intakes over10 liters of whole milk a day. This amount of milk is fed in 8 to 10 meals, each of them lasting about 10 minutes. The calf has a possibility of intaking such a big amount of milk for as long as 10 months and the weaning is a gradual process. In practical conditions the amount, number and overall duration of liquid feeding is very different than the natural ones. As a result, feeding whole milk to calves, however close to nature may seem , in farming conditions is very far from that model. This  fact is an additional argument for replacing whole milk for calf milk replacers in practical feeding.

Pros of using milk

  • High digestibility
  • Presence of biologically active components

Cons of using milk

  • Risk of spreading diseases in herd, especially if it is waste milk ( even if pasteurized)
  • Variable levels of protein and energy
  • Necessary supplementation with vitamins and minerals
  • Increased resistance to drugs in case of using milk from animals undergoing treatment
  • High cost in the case of whole milk

Costs are important

In the discussion on the type of liquid feed for calves we have to mention that feeding the animals with calf milk replacers is usually two to three times cheaper than feeding them with whole milk. Lower cost of calf feeding with milk replacers come not only from the lower price ( if compared with milk) but also lower costs tied to the organizing of the feeding on a farm.

To reduce breeding costs, some breeders use waste milk ( such as colostrum surplus, transitional milk, milk with high number of somatic cells or, which is the worst, milk from cows undergoing medical treatment). They tend to justify such practices by ‘’feed management’, which apparently, costs them nothing. Such practices are extremely risky and must definitely be avoided. The number of pathogens leading to calves’ diseases is usually very high in waste milk. There is no 100 % guarantee that waste milk is secure, even after pasteurization, which is inefficient in fighting f.ex. paratuberculosis . The process does not destroy protozoa, resting spores of microorganisms (oocysts), bacterial toxins and remains of antibiotics. Waste milk may be the source of pathogens ( i.e. Escherichia coli, BVD, Listeria monocytogenes), staphylococci and salmonellosis. On top of that, feeding calves with milk containing antibiotics increases the probability of drug resistance occurrence in the herd. The variable composition of waste milk is yet another disadvantage of this feeding method.

Summing up, feeding calves with the highest quality calf milk replacer allows to rear healthy and well-developing animals and ,at the same time, reduces the rearing costs, which is a unique standard in modern feeding of this animal group.