J.E. Nocek

The Influence of Feeding Frequency on Ruminal Parameters and Production Response in Dairy Cattle

Summary The effect of feeding frequency on ruminal parameters and milk production in dairy cattle was reviewed. Increasing feeding frequency generally resulted in a less variable diurnal profile in ruminal pH. Feeding a TMR more frequently did not result in reduced variation of diurnal pH pattern. Forage to concentrate ratio influenced the volatile fatty acid concentration associated with increased feeding frequency. Generally diets containing higher proportions of concentrate (►60% of DM) showed a higher ruminal acetate to propionate ratio with increased feeding frequency. Parameters such as water intake, microbial activity, ruminal digestion and dilution rates were either not affected or positively influenced by increased feeding frequency. Possible modes of action to increase milk yield may be through enhanced efficiency of microbial synthesis and yield and/or increased escape of potentially degradable protein through increased ruminal dilution rate, and/or increased energy intake. A summary of 9 studies revealed that increasing feeding frequency from 2 to 4, 5 or 6 times daily resulted in a slight increase (1.5%) in milk yield. In eight studies, the average increase in milk fat concentration was 6.8%. The primary effect of increased feeding frequency on fat concentration was associated with diets low or marginal in fiber, high in concentrates, and where milk fat was originally depressed. Increased feeding frequency may be of most potential benefit in early lactation, high-producing cows that are in an energy deficient status, where fat depression is of key importance.

New Concepts in Carbohydrate Nutrition for High-Producing Cows1

Abstract Structural carbohydrates: acid detergent fiber (ADF) and neutral detergent fiber (NDF) are utilized in dairy ration formulations as negative indicators of energy density. NDF has been identified as a predictor of dry matter intake, and ADF related more to digestibility. However, predictability of intake and digestibility from chemical parameters varies widely with forage type. Nonstructural carbohydrates (NSC) are a major energy source in high- producing-cow diets. Starch comprises the major portion of the total ration NSC fraction. Processing can influence rumen degradability of starch. Enzymatic methods and difference equations have been developed to quantitate NSC. Production studies have shown an optimal level of NSC to maximize milk yield. Rumen degradable carbohydrate/starch are emerging as qualitative measures in formulating dairy rations. Their usefulness in fine-tuning nutrient availability to the dairy cow for production purposes will be enhanced as larger data bases are developed and more production studies are conducted. The synergism between protein and carbohydrate use at the ruminai, pos- truminal, and mammary gland level will ultimately be key in maximizing efficiency of milk yield in dairy cattle.

Bovine Foot Anatomy: A Functional and Practical Perspective

Summary The subsequent discussion is not intended to be a comprehensive review of feet and leg anatomy. It is, however, an attempt to bring about an awareness of the various parts of the cow’s foot not usually visualized to help illustrate their function and vulnerability to injury and disease. Each digit is composed of three primary (distal, middle, and proximal phalanxes) and three secondary (navicular, and two sesmoids) bones. Ligaments are composed of elastic connective tissue that bind bone to bones. The cruciates are major ligaments binding together the two digits of the foot. Several flexor and extensor tendons (attach muscles to bones) coordinate the movement of the foot. The corium is a sensitive vascular layer of tissue which serves to nourish and connect the internal aspects of the foot to the hard keratinized protective outer wall. It can be realized that with so many moving parts, there are innumerable opportunities for injuries with resulting lameness to occur. Just because external signs of lameness such as cracks or abscesses may be absent from a lame cow’s foot does not mean there are no other reasons for lameness.

Management of Foot and Leg Problems in Dairy Cattle 1

Summary There is no one single cause of foot problems. Likewise, there is no one specific cure. The key is prevention, and only through diligent management practices associated with environment, nutrition, breeding and health programs can prevention be accomplished. Guidelines for foot management: 1. Observation: routinely observe cows for any apparent lameness, standing problems, or if they are lying down excessively. Also, provide an environment conducive to proper foot wear (i.e., get cows off concrete at least two hours per day, groove smooth floors, grade rough floors). 2. Monitor nutrition and breeding programs: balance diets for specific groups of cows according to National Research Council recommendations. Choose sires with high dollar product value, which also have high stayability and feet ratings. 3. Prompt treatment of disorders: treat lame cows as soon as they are noticed, not when they become a nuisance. Also, treat cows with infectious diseases (metritis, mastitis) promptly. 4. Maintain a regular hoof trimming schedule... every six months to a year depending on hoof growth and wear. 5. Provide a foot bath for cows, that is maintained on a daily basis.