The early growing phase of a heifer should be considered as one of the most critical phases of her life, with potential impact on growth and production for years to come. Several scientific publications have proven the positive relationship between early phases of heifer rearing and performances of the adult cow. For example, a famous meta-analysis of Soberon & Van Amburgh has concluded that ‘for every kilogram of pre-weaning average daily gain, calves produced 1,551kg more milk during first lactation’. The pre-weaning period is so crucial because it is a period of development for the organs; no compensatory growth occurs during this time. If a delay is experienced during this formative period it cannot be made up for and that potential is gone for good. If the rumen does not develop well at that time its mature size might be affected, as well as the intake capacity of the adult cow. This phenomenon is even more critical with modern high genetics HF cows: genetic potential must be expressed not to remain virtual. Early growth is also an important factor to reduce the age at first calving. Earlier calving is a very efficient way to reduce the cost of heifer rearing. In fact, reducing the heifer raising period from 24 months to 23 months saves approximately $93 per heifer.
If the early phases of heifer development are not well managed, a part of their potential will be erased. This will lead to disappointment and loss of income for the farmer.
Calf starter is essential for rumen development
Calf starter plays a major role in this pre-weaning phase. When milk bypasses the rumen and goes directly in the abomasum, calf starter reaches it and initiates fermentation. This has a strong positive effect on establishing the rumen microbial population, which is so important for ruminants. Those fermentations produce volatile fatty acids, which are absorbed through the rumen wall and thus stimulate early development of rumen papillae. Classic trials at Cornell University have shown that concentrate promotes this development, while forage has almost no effect. The formulation of calf starter should be designed to promote rumen development, including a specific selection of nutrients. Micro-nutrients, such as vitamins, trace elements and antioxidants favor good immunity and vitality of calves. The objective of this formulation is also to prepare the transition after weaning, which is a critical period and source of stress for the calf. Palatability is also a key factor of success for calf starter. The use of a powerful sweetener is key to stimulate the intake of calf starter, as calves are sensitive to taste and enjoy sweetness. They indeed have a large number of taste buds (see Table 1). This preference for sweetness could reflect a strategy to obtain dietary energy.
High quality milk replacer eases weaning transition
The use of a good quality milk replacer remains the best option for the dairy farmer in a ‘normal’ market situation. As modern Holstein cows have been intensively selected for decades, their milk is probably no longer the best meal for young dairy calves that must be weaned early. For example, the fat to protein ratio and balance of micro-nutrients is not optimal for them. A good quality milk replacer should be highly digestible, well balanced in amino acids and trace-elements, highly palatable and free from antinutritional factors. It should also help to promote the early consumption of solid feed, which is the golden criterion for smooth weaning. The use of soluble milk proteins allows smooth curds in the abomasum and quick digestion of milk which promotes the appetite for solid feed. To provide high security and compensate for comparatively lower production of lactic acid in the abomasum than high casein milk, a combination of organic acids allows the pH in the intestine to decrease and prevent the development of bacteria.
Targets of a calf-heifer program
A good calf-heifer program aims to improve heifer health by decreasing digestive issues, optimize growth by fulfilling nutritional requirements, and foster rumen development. The objectives of the farmers can be more specific and may include things like a desire for early weaning, time and money savings, and/or maximum performance in accordance with premium quality genetics.
Experts at Wisium have considered all the important points for a successful rearing phase of dairy heifers and, through their Nursy programs, offer different options to dairy farmers. These options depend on the strategy they wish to adopt. Nursy nutritional programs propose a complete and packaged solution that is dedicated to a heifer, with three options:
- Flex, for a classical program focusing on security
- Quick, for an early weaning program
- Advance, for a high-performance program
These programs are based on a combination of Nursy specific starter feeds and associated highly digestible Newean milk replacers. Different additives included in these programs are extremely helpful to improve the performance of calves and address some specific issues. For example, a trial done in Mexico with the Nursy Flex program showed a significant improvement of rumen development compared to a standard program, with 1 cm more length and 5 cm more width after 30 days of life, and 6 cm more length and 1.5 cm more width after 60 days (2×2 calves were sacrificed after each period).