The increase in nutrient requirements during the late-gestation period is significant in cows. Depending upon the animal’s mature weight, crude protein requirements jump 28% to 30%, while total digestible nutrient requirements jump 15% to 17% between the seventh and ninth months.
• Cows in late gestation have greater nutritional needs.
• Be prepared by knowing cow weights and nutrient demands.
• Producers also should know the nutrient content of their feed.
Nutrient deficiency during this period can result in weak calves that are more susceptible to environmental stresses and cows that are slow to breed back. Failing to provide late-gestation cows with a ration that meets their nutrient requirements will negatively impact the potential profitability of the cow-calf operation. Thus, the cattle manager must prepare for those increased nutrient needs. Preparation involves knowing the weight and nutritional status of the cow, knowing the diet nutrient requirements and knowing the nutrient content of the feedstuffs being used.
Cattle nutrient requirements, as provided by the National Research Council subcommittee on beef cattle, vary depending upon the animal’s mature weight, age and production stage. Larger-frame, heavier animals have higher daily nutrient requirements than smaller-frame, lighter animals. Pregnant replacement heifers and 2-year-old cows have higher nutrient requirements than mature cattle at similar production stages.
Examples of CP and TDN requirements for the last 60 days of gestation (eighth and ninth months) for mature and growing cattle are provided in the above table to illustrate this point. The nutrient density requirements are based on a dry matter intake of approximately 2% of the animal’s body weight.
Several observations can be made from studying the table:
• The nutrient density requirement of the diet does not vary greatly between weight classes of similarly aged animals, but nutrient density requirements are higher for younger animals that are still growing. This reflects the relationship between body weight and a dry matter intake based on a percentage of body weight.
• The total amount of nutrients (pounds per day) required increases as animal body weight increases for both mature and growing animals.
• Both the nutrient density and the amount of nutrients (pounds per day) increase as gestation advances.
The take-home management message is that the mature weight of the cow should be known to ensure adequate nutrients are being provided. Although many cattle producers think they have 1,200-pound (or less) cows, there are many 1,400- to 1,500-pound cows out in the countryside. At a meeting a couple of years ago, a speaker said most 1,200-pound cows actually weighed 1,500 pounds, and most 1,000-pound round bales weighed 750 pounds. You have to measure and weigh if you want to do a good job of managing.
Feeding to meet the needs of a mature cow will put the younger, growing cows and heifers in a nutrient-deficient state. On the other hand, feeding to meet the needs of the younger cows and heifers will mean mature cows are being overfed. Both situations are costly. Grouping cows according to age and production stage allows more targeted feeding and better economical use of feed resources.
In practice, particularly with smaller herds, many farmers feed hay free choice to the entire herd. If the hay is close to the required nutrient density, cattle often will eat more than the 2% of body weight figure. This may allow the younger, growing animals to meet their daily pounds of nutrients needed, but it means the older animals are overeating.
Besides knowing your cow weights and nutrient requirements, preparation for late gestation involves knowing the nutrient content of the hay, stockpiled forage or other feedstuffs that may be used. It’s hard for farmers to economically match nutrient needs without this information.
The eye of experience and close detail to body condition can help managers make good feeding decisions. When used with knowledge of animal weights, nutrient requirements and feedstuff nutrient analysis, the combination can increase profitability.
Lewandowski is with Ohio State University Extension in Athens County.
* Projected mature weight
Source: National Research Council for Beef Cattle
This article published in the February, 2010 edition of OHIO FARMER.
All rights reserved. Copyright Farm Progress Cos. 2010.