This journal club episode comes to you from the 2024 Tri-State Dairy Nutrition Conference. The paper is “Major Accomplishments in Calf Nutrition and Growth” from the conference proceedings.

Accelerated milk feeding of calves results in about a thousand-pound first lactation production increase. The mechanism is unclear: it could be isolated to the mammary gland or related to the functional ability of the digestive tract and liver to support lactation. Economic analyses have shown an advantage of $205 per calf. (6:04)

Regarding amino acid requirements of dairy calves, whey-based milk replacers require additional methionine; lysine is also common. Threonine can be limiting in soy-based milk replacers. Establishing amino acid requirements was beyond the scope of what the NASEM committee could do, and more data is probably needed for calves. However, CNCPS has amino acid requirements defined, so it’s possible to get in the ballpark for amino acids. (12:00)

What about feeding hay to young calves? The latest research has shown calves only over-consume alfalfa out of all the common forages. A study in Spain showed when offered alfalfa, calves consumed 14% of their total dry matter from alfalfa, decreasing the amount of starter they consumed. When offered grass hay or straw, calves only consumed 4-5% forage and they actually boosted starter intake and overall feed efficiency. Dr. Drackley recommends starting grass hay, wheat straw, or similar forages at 2-3 weeks of age. It should be just a sprinkling top dressed on their starter, or about 5% of the total if you’re feeding a mixed diet. (15:08)

Dr. Drackley covers five major accomplishments in this paper. (18:06)

1. Knowledge of colostrum, highlighting the establishment of different categories for passive transfer (excellent, good, fair, and poor) rather than just a yes or no. The four categories relate very well to the mortality and morbidity associated with young calves. 
2. Feeding more milk to young calves, highlighting a 2001 paper from Dr. Mike Van Amburgh’s lab that was the eye opener for the industry. 
3. The publication of the NRC in 2001, which had a separate chapter for calves, was perhaps the first time people started to think seriously about calves.
4. Major growth in behavior research, particularly related to feeding behavior, shows calves fed conventional, limited amounts of milk are hungry as demonstrated by vocalization and increased restlessness.
5. Publication of NASEM 2021.

From a welfare research perspective, Dr. Drackley thinks cow-calf separation and group vs hutch housing will continue to be issues of concern for consumers. In Europe, there’s demonstration research keeping calves with cows during the milk-feeding period. (20:44)

What about the post-weaning slump? The big issue is weaning too early before starter intake has increased adequately. Weaning at eight weeks instead of six weeks results in an improvement in total nutrient intake. A gradual step down in the amount of milk provided will also stimulate starter intake. Starter quality and composition is critical, and water availability can be an issue for many farms. (23:29) 

Concerning colostrum, a big advancement has been a better understanding of what colostrum does in addition to establishing passive immunity. The nutrition aspects of high protein, vitamins, minerals, and growth-promoting ingredients like hormones, growth factors, and cytokines all play a major role in calf health and development. Measuring colostrum quality is better and easier with the use of refractometers. Recent emphasis on how easily colostrum can be contaminated and how that negatively affects the calf has also been crucial. As much as we know about milk synthesis, we know very little about colostrum synthesis. Adequate metabolizable protein is important for quality and quantity, and immune-related vitamins and minerals are important. Beyond that, we do not have a good understanding of what regulates colostrum, particularly volume. (25:50)

What’s next in calf nutrition? Establishing a good amino acid model and trying to minimize both costs and nitrogen excretion, colostrum quality and quantity from the cow side, continued research into workable systems for accelerated milk feeding with a smooth weaning transition, and post-weaning feeding programs are areas where Dr. Drackley predicts fruitful research opportunities. (31:36)

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