FROM THE FARM REPORT: WARDING OFF WEANING WOES

Weaning is ubiquitous in the dairy industry and is not exclusive to only heifer calves but also beef crosses and bulls. In that context it’s a transition period of great importance for all these animals. We can either get it right and continue the projected path set in the preweaning period for growth and health, or weaning can be a challenge to these animals and can go off the rails.

This transition from a non-ruminant to a ruminant in a relatively short period of time is certainly a big feat. We push this transition by weaning several months earlier than would “naturally” occur if the calf was suckling from the cow, therefore speeding up the timetable to develop the gastrointestinal tract.

The gastrointestinal tract goes from 6-7% of the body when the calf is fed milk and small amounts of starter to over 15% when the calf is weaned and consuming solid feed. This change in gut contents alone can account for 0.5-0.7 lb/d (0.2 to 0.3 kg/d) alone and isn’t captured in empty body weight gain of this animal. This can add up to 25 to 30% of average daily gain for a 10-week-old animal. In the preweaning period the rumen can represent 1.3-1.8% of empty body weight (body without the digesta in the gastrointestinal tract). However, after weaning it can be 15-23%.

There’s obviously a critical need for solid feed consumption in the preweaning calf to make it successfully through the weaning and postweaning period. While size of the gastrointestinal tract is a consideration, the function and ability to utilize the nutrients consumed from solid feed is most important for developing the gastrointestinal tract and allowing the animal to use nutrients consumed to support maintenance and growth requirements during this transition.

Some critical things to focus on the ward off weaning woes-

Starter quality. Starter is critical to rumen development and facilitation of weaning. It should provide fermentable carbohydrates to produce volatile fatty acids (propionate and butyrate) which drive ruminal epithelium development. The first quality control is if the calf consumes it. Some of the most palatable ingredients are wheat meal, sorghum meal, barley meal, and corn meal for cereals and soybean meal and distillers grains for protein sources. Physical form may play a role in degradation rates with texturized starters promoting a higher rumen pH than pelleted or ground starters. Starch should range 22-38%, protein from 20-25%, neutral detergent fiber > 15%, sugar 10-15% (molasses limited to <7.5% of the formula), and fat <5%.

Weaning age. Surprisingly, calves can be quite resilient to different weaning ages. What might make or break success of a weaning age is linked to starter intake prior to weaning. During and after weaning a calf needs to consume an adequate amount and quality of starter to maintain growth realized in the preweaning period. Cumulative non-forage carbohydrate intake prior to weaning should be >33 lb (15 kg) or total dry matter intake >60 lb (28 kg). The milk allowance and weaning schedule will largely dictate if calves reach this target at a specific weaning age.

Weaning duration. Weaning duration is very closely linked to both milk allowance and observed starter intake. Often a 10-day weaning period is optimal on higher milk allowances to facilitate more consumption of starter. A starting point could be to decrease high milk or milk replacer allowances by steps of 25% per week until weaning to increase starter intake consumption.

Forage. There is a balance of how much forage to include in the diets of weaning calves. There is limited nutritional value realized from most forages for animals at this age, however there could be several benefits in terms of ruminal health and function with the addition of a forage. Ideally, forage intake should be limited to 10% of less. There have been benefits noted when grass hay or straw has been proved in terms of starter intake and average daily gain. Alfalfa is generally poorly utilized by these animals and often displaces starter intake and consumption of digestible nutrients.

Weaning is one of the most important transitions for young ruminant animals on our farms. Adjusting strategies to optimize this transition is important for maintaining growth during this time. Focus combining starter quality, weaning age, weaning duration and forage so that we set these animals up for success and ward off any weaning woes.

— Sarah Morrison

morrison@whminer.com