by Jacques Potgieter

 

Efficient milk production is the key focus of any dairy operation. To ensure our aim of efficient milk production it is essential that calves and heifers are grown out properly and timeously. As the profitability of the dairy industry becomes more under pressure and dairy farms increases in size, the economics of calf and heifer rearing systems has become a vital aspect of the farms profitability. Accelerated growth can be used in the context where specific management goals are met within a specific timeframe. Production goals such as the target weight and age at which a group of heifers is to be confirmed pregnant will indicate the age at first calving. There are many factors such as the quantity and quality of colostrum and milk fed to the calves together with the quality of the starter (E.g. the type of protein in the starter) which all will affect the end goal.

The first day, especially the first few hours of a calf’s life are critical to its health and survival. Failure of passive transfer of antibodies will have a delayed effect on time to first calving, lower average daily gain (ADG) up to 6 months and will impact milk production as well as the quality of milk negatively during the first lactation.

High quality colostrum will have a specific gravity value of > 50mg/ml IgG or Brix value of at least 22% (Colostrometer). Ideally, the first feeding of colostrum must be fed to calves within 30min after calving and the second feeding within 6 hours after the first feeding. Calves should be fed 10% of bodyweight (4L) at first feeding and 5% of bodyweight (2L) at second feeding. Research indicated that a calf fed colostrum for the first 4 days will be more efficient, growing faster and potentially producing more milk per lactation over her lifetime.

Traditionally, calves have been fed limited amounts of milk or milk replacer to stimulate early intake of starter and to minimize input costs (conventional system). Some of the disadvantages of the conventional milk feeding systems are decreased efficiency of body size gain, increased time to breeding and first calving, decreased ability to withstand infectious challenges and lower milk production during the first and second lactation.

Accelerated calf growth programs (intensified early nutrition programs) involve feeding calves higher amounts of milk during the first 60 days compared to the conventional 4L per day (Holstein calves) and 3L per day (Jersey calves) in combination with a high-quality starter. Milk feeding rates are approximately twice those of conventional systems. If a milk replacer is being used it is important to take note of the protein quality (Whey and Skim Milk powder), without plant-based proteins, Ash is less than 10% of dry matter, Fibre less than 0.15% and avoid high amounts of free fatty acids and polyunsaturated vegetable oils.

Epigenetics play a major role during the pre-weaning period. Research indicates that for every gram a calve grows above 450 grams per day from birth up till weaning will result to a minimum of 1L/gram above 450 grams growth per day, additional milk in the first lactation. E.g., if a calve has an average daily gain of 1kg/day in the pre-weaning period she is most likely to produce 550 Liters more in her first lactation. Calves should at least double their birth weight and consume a minimum of 1kg starter for three consecutive days at weaning.

Access to ad libitum fresh water is crucial from day one as it encourages early consumption of the calf starter and stimulates higher total feed intake.

Heifers should weigh 55% of the average mature weight of the milking herd (4th plus lactation) at breeding. Body weight and sexual maturity should be the determining factor for breeding and not age. The benchmark for the weight of a heifer at first calving should be 85% and 92% at second lactation of mature body weight.

 

Conclusion:

The concept of accelerated feeding for young milk-fed calves is now well-accepted as an alternative to traditional restricted feeding. The correct accelerated growth program will result in a calf that will grow faster, reach her age at first calving sooner (< 24 months) and will have increased milk production. We cannot change the genetic merit of our heifers, but we must assure that her full genetic potential can be reached as a lactating cow.