The calf starter ration, to compliment an intensive calf management program, needs to be highly palatable and of excellent quality. When a high protein milk replacer (26%) is being fed, the calf starter should be at least 22% protein to maintain optimal growth. It is critical that protein needs must be met to help maintain early growth rate advantage and prevent development of fatty udders. In raising dairy heifers, the major goals of feeding before weaning are to:

• Feed for optimum health and strong immunity
• Encourage the intake of starter
• Have good skeletal development
• Develop rumen activity
• Prepare the calf for weaning

Extending the liquid feeding period to 7-8 weeks can achieve higher gains prior to weaning and a continued benefit post weaning. The ability of the calf or the desire by calves to consume dry feed (starter) is in direct proportion to the volume of liquid feed being offered. To help prevent the weaning stall out, reduce the volume of liquid being fed to achieve a starter intake of 900 grams per calf per day, for 3 consecutive days prior to weaning. A calf should not be weaned until its rumen is functional and capable of supporting all of its nutritional needs. Normal and early development of the rumen requires:

• 1. Bacteria
• 2. Liquid in the rumen
• 3. Absorptive ability of rumen wall tissue

Bacteria

Bacteria begin to grow in the rumen as soon as the calf begins to eat. The types of bacteria that develop are dependent on the type of feed that the calf eats. Milk supports aerobic bacteria development, while dry feed supports anaerobic bacteria. It is anaerobic bacteria that are necessary for proper rumen development and function.

Liquid in the Rumen

Bacteria in the rumen can only survive in a water environment. Most of the water that enters the rumen is from free water intake. Milk or milk replacer does not constitute free water. They bypass the rumen due to the oesphageal groove that is active until 12 weeks of age. The intake of water stimulates dry feed intake, thus the availability of clean fresh water is critical to dry matter intake and overall calf health and performance.

Kertz, A.F. 1984 J.D.S. 67: 2964-2969

Absorptive Ability of Rumen Wall Tissue

The absorption of end products of fermentation is a very important part of rumen development. The energy requirements of the new-born calf are met from absorption of glucose from the abomasum. There is little or no absorption or metabolism of volatile fatty acids (VFA) in neonatal calves. The rumen must develop this ability prior to weaning. The rumen consists of two layers, the epithelial layer and the muscular layer. The muscle layer is responsible for rumen contractions and gives support to the epithelial layer. The epithelial layer of the rumen wall is the absorptive layer. End products (VFA) of ruminal fermentation, particularly propionate and butyrate, provide the stimulus needed for epithelial development. Calves denied access to dry feed will not develop a functional rumen. It is grain intake rather than hay/straw intake that is important to ensure rapid rumen development and a smooth transition at weaning time.

Calf time line and rumen development

*Primary organ, ** Primary nutrient weaning

General Guidelines

• A good quality palatable starter (min 22% protein) should be on offer from day 5.
• Feed to appetite, with frequent fresh ‘top ups’, is preferable to ad lib feeding.
• Calves prefer to have calf starter in a shallow bowl, one in which they can scrape their tongues under the grain. They consume more starter when they are able to reach the bottom of the container. Deep containers are less attractive to calves as accumulated feed becomes spoiled with saliva and calves find it physically more challenging to get at the feed.
• All buckets and containers should be emptied and cleaned daily.
• Calves should not be weaned until they are eating 900 grams of starter per day for 3 consecutive days.
• Calf starter with considerable molasses may freeze in winter into frozen lumps and may clump in the hot humid summer months.
• Calf starter with excessive molasses may attract flies in the summer.
• Pelleted calf starter may crumble. Fines from old pelleted calf starter are especially unpalatable for calves. Pelleted calf starters are excellent feeds, but it becomes very important for daily replenishment.
• Ensure adequate fresh, clean water is available.