New Zealand data shows that only 36% of our heifers meet pre-calving weight targets.
This is significant as there is an approximate 2kgMS production loss per year for every 1% they are behind this target, and poorly grown heifers are unlikely to survive to the end of their second lactation, so won’t remain in the herd long enough to become profitable. So what can we do to ensure our stock are meeting these critical targets? The answer, surprisingly, lies in calf nutrition.
With the current state of the economy, it may be tempting to tighten the belt and save some pennies in the calf sheds, but this will cost in the long run. This is due to the high costs associated with compensatory growth, not achieving liveweight targets, and by missing opportunities to maximise milk production, survivability and thus profitability within your business.
Feed conversion efficiency of calves is significantly higher than when they reach adulthood, meaning a 2-week-old calf will eat 100g of feed and grow 50g, where an 11-month-old will eat that same 100g and only grow 9g. This means the most cost-effective time to grow your cattle is pre-weaning. Studies looking into the costs of raising heifer calves till first calving, found rearing costs were reduced by $60 each when calves were fed 6L milk per day compared to 4L of milk per day pre-weaning. This is due to how efficiently young animals convert milk to growth and how inefficient compensatory growth in adult grass-fed cattle is by comparison.
Accelerated pre-weaning growth not only facilitates earlier weaning, but also positively impacts on subsequent growth due to the impacts on digestive efficiency. Studies following calves from birth till maturation found noticeable differences in post-weaning average daily gain (ADG) and the age at which heifers reached mature weight, based solely on how they were fed pre-weaning. Calves with higher ADG during milk feeding went on to grow faster after weaning and achieved mature weights 1-9 months earlier than those with lower pre-weaning ADG, despite eating the same diet after weaning.
Additionally, accelerated early growth positively influences udder development by reducing fat deposition and increasing the number of alveoli. This may explain up to 22% of the variation in first lactation milk yields. This means the pre-weaning diet exerts a larger impact on milk yield than genetic selection for production does. Data shows that for every extra gram of pre-weaning ADG we get 4.8L more milk, a whopping 818L over the first lactation!
So how do we achieve accelerated pre-weaning growth? Regardless of what you will be feeding, the goal is the same. You want to be achieving 900g ADG in order to have doubled your calf’s birthweight by weaning at 8 weeks. Volac’s website “feed for growth” has specific guidance on how to achieve this if you’d like further information, but these are the feed intakes you should be aiming for
When deciding which calf milk replacer (CMR) to feed you’ll need to choose between traditional casein-based CMR’s or newer whey-based powders like Blossom Hi-Spec. The main differences are digestibility and their influence on calf immunity to scours. Casein-based CMR’s form a curd in the abomasum which is then broken down and digested. This curd-forming ability differs between brands based on ingredient quality and processing conditions, meaning you get what you pay for. Whey-based powders don’t form a curd prior to digestion, leading to both improved nutrient absorption and earlier meal intake compared to casein-fed calves. Whey-based CMR’s like Blossom Hi-spec, also contain high levels of functional bioactive proteins like lactoferrin and immunoglobulins, and a complete micronutrient profile that casein-based feeds simply do not. These positively influence growth, immunity and provide localised protection within the gut from scour causing pathogens. Overall, when comparing casein-based and whey-based CMR’s of similar quality and volume fed you can expect similar calf growth, but the real benefit of whey-based CMR’s is the reduced incidence of scours, which can save you both time and treatment costs.
Feeding whole milk alone can limit calf growth and contribute to nutritional scours, due to fluctuating dry matter content, high fat percentages and an incomplete micronutrient profile. Studies comparing calves fed either 4L whole milk or 4L whole milk fortified with 300g of Blossom Hi-Spec, found that calves fed fortified milk experienced 5% less disease, 2% less deaths and were 5kg heavier at weaning. The overall effect of adding just 300g CMR/ day boosted overall dry matter content by 52%, protein by 53% and energy by 45%, giving calves more energy to put into growth and their immune systems. Overall, fortifying whole milk with CMR’s is a very cost-effective way to maximise early growth in your calves.