Have you ever wondered why breeding stock from different areas or in different seasons perform better than their contemporaries? Elders Livestock Production Manager Rob Inglis shares his tips for effective weaner nutrition management.
As the master forger said to the art thief, ‘It’s in the frame’. Skeletal mass has a pronounced influence on both muscle development and reproductive rate as the skeleton is the principal repository for key minerals required for growth and reproduction. Skeletal growth is literally on steroids during weaning.
Weaner management begins at conception
The body condition score of a cow or ewe at joining and during the first trimester of pregnancy, has a profound effect on birthweight, and milk production during lactation. In fact, it sets the foundation for weaning weight. This becomes a self-perpetuating cycle. Heavier offspring at 12 weeks enables earlier weaning, which enables more recovery time for dams, meaning better conditioned ewes and cows (condition score greater than 3.5) at subsequent joinings – usually with a lower feed requirement to achieve said goal.
Some things to consider:
- It is cheaper to supplementary feed a weaner than a pregnant or lactating cow or ewe.
- It takes twice as much energy to put condition on as it does to maintain it.
- The cows or ewes which wean the heaviest progeny will lose the most condition during lactation.
Weaning
Variation in weaner weights is inevitable. A single lamb born of a mature ewe could be as much as 20 kg heavier than a late twin born out of a maiden ewe, in a 5-week joining. Likewise, there could be up to an 80kg differential, on a 6-week joining, between an early born calf from a mature (6 tooth or greater) cow born at the start of calving, and a late born heifer calf.
- Single early born: Birth weight 5.5kg + (300g/day growth x 77 days) = 28 kg
- Late twin born: Birth weight 3.5kg + (150g/day growth x 45 days*) = 10 kg
- Mature cow, early calf: Birth weight 40kg + (1.25 kg/day x 140 days) = 210kg
- Heifer, late born calf: Birth weight 35kg + (1.0 kg/day x 100 days) = 135kg
Should these calves and lambs be weaned?
The heavy lambs or calves? Yes. There is ample evidence to support the fact that once calves or lambs have reached 33 per cent (pc) and 40 pc respectively of their standard adult reference weight (SRW), their rumens are sufficiently developed to thrive without milk. For a typical Angus cow (SRW = 550kg) or Peppin Merino (SRW = 65kg) that equates to 180kg and 26kg.
The light calves or lambs? Yes, however these lighter animals will require a supplementary concentrate to augment their protein requirements.
The clear solution is to draft weaners into at least three mobs, according to weight.
Each of these mobs will have different protein and energy requirements, and a supplementary ration tailored to suit the weight and required growth rates of each group. This is stock in trade for a livestock production advisor.
For steer calves and wether lambs, once they have reached the benchmark 33 pc and 40 pc Standard Reference Weight (SRW) further growth is a little less important, as compensatory growth can cover early growth inertia later on. For heifer and bull calves, and ewe and ram lambs however, and even growth trajectory during puberty is critical as shown on the graph below.
Graph showing the desired growth trajectory for a heifer calf and weaner (SRW 600kg) from birth to first calving.
Puberty and skeletal development
Under optimum nutritional conditions, bone growth almost doubles during puberty. To counter that, nutritional stress will stifle it. While the roles of calcium, Vitamin D and phosphorous and a number of micro minerals in skeletal development are well known, perhaps what is less appreciated is the role of collagen, a protein, in bone structure.
Protein deficiency during puberty compromises collagen – the matrix upon which the inorganic bone is constructed – which limits the amount of hydroxyapatite (ostensibly calcium and phosphorous) which can be amassed. Bone is the body’s repository for calcium and phosphorus the minerals of greatest importance in growth and reproductive performance.
A diet which is balanced for both energy and protein and contains the requisite minerals and vitamins is imperative for weaner growth and development, particularly during puberty.
Early weaning
Where or when seasonal conditions are less than ideal, which is currently true for many parts of southern and western Australia, weaning before calves or lambs reach the aforementioned benchmark weights is advisable. Early weaning has proved to be both beneficial to dam and offspring. Among the many advantages of early weaning, the two most significant are:
- reducing the effective stocking rate – an important consideration where feed on offer is limited.
- preservation of females – reduction of condition score during a prolonged lactation will compromise subsequent reproductive success.
For further advice, contact your local Elders Livestock Production Specialist.
Please note: this article contains information of a general nature, and does not take into account your personal objectives, situation or needs. Before acting on any information, you should consider the appropriateness of the information provided, and seek advice on whether it is fit for your circumstances.
