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on June 28, 2010

Improving cow-calf nutrition

Proper feeding practices increase efficiency and body condition score.

The U.S. cow-calf herd is at a 60-year low, attributed to droughts in the Midwest and South, high grain prices resulting in conversion of pasture to row crops, low feedlot margins and the retirement of elderly ranchers. Consequently, the beef industry is set for record profits over the next five years. This will be a welcome relief from the previous five years, which have been some of the most difficult ever for the beef industry.

Reproductive efficiency is a major determinant of the profitability of a ranch and is represented by the proportion of cows becoming pregnant at the least cost. Factors that affect reproductive efficiency include weather, age, semen quality, and nutrition. The plane of nutrition and body condition score (BCS) affect the post-partum anestrous interval.

After a 285-day gestation period, the cow has approximately 80 days during which to re-breed to remain in a 365-day reproductive cycle. Cows attaining a BCS 5.5 or greater at calving and are in positive energy balance and are likely to have a short postpartum interval. Cows at a BCS of 4.5 or less at calving are unlikely to become pregnant and conform to the 365 cycle than a BCS 5.5 cow due to loss of condition prior to breeding. A cow at a BCS of 5.5 at calving maintaining her BCS through breeding, is more likely to conceive in the first 21 days out of the breeding season.

Calves conceived in the first estrus cycle post-calving wean off 32 pounds heavier than calves conceived in the second cycle and 80 pounds heavier than calves conceived in the third estrous cycle. Consider a herd of 100 head with a 15% replacement rate and a sale price of $1.20 per pound for feeder calves. If there is a 15% increase in calves born in the first 21 days, the farm will bring in an additional $490 profit over calves born 21 days later and $1,225 over calves born 42 days later.

Economical nutrition  

The question is: “How do you keep cows at a BCS of 5.5 or better without breaking the bank?” In the Midwest, feedlots have fed distillers’ grains or gluten feed for many years. This approach is relatively new to the cow-calf industry. Distillers’ grains or gluten feed are good sources of energy, protein, and phosphorus for beef cows. These co-products are more economical than buying protein tubs or range cubes (cake).

Feeding these co-products often eliminates the need for additional phosphorous or protein, providing vitamin B and mineral requirements are satisfied. Assay of hay or silage will determine the amount of co-products needed to balance the diet and if any additional phosphorous will be required. Distillers’ grains have been shown to significantly improve artificial insemination pregnancy rates in beef heifers.

Supplementing the diets of dams during gestation also has lasting effects extending to the gestating heifer calf. Heifer calves from dams grazing on low-protein dormant range that were supplemented with protein three times per week were of similar weight at birth as calves from non-supplemented dams.

However, their adjusted 205-day weight was 17 pounds heavier and the weight when pregnancy was confirmed was 32 pounds greater for heifers from supplemented dams. First service conception of heifers from supplemented dams was 88% and overall pregnancy rate was 94% compared with 45% and 73% for heifers from non-supplemented dams. Supplementation of protein in late gestation does not increase birth weight, but does improve weaning weight of the calf and reproductive performance of their female calves.

Improving efficiency

Forages are the principal energy source for beef cows in most production systems. In many situations, forages are insufficient to meet protein and energy demands of late-term gestating or lactating cows. Cows fed diets providing 11, 14, or 17 pounds of TDN had calves with birth weights of 58, 62, or 64 pounds, respectively.

A reduction in the incidence of dystocia (assisted births) was observed when comparing the low energy diet with a medium or high-energy diet. Cows that calve down unassisted have a 16% advantage in pregnancy success. In addition, cows experiencing a labor of short duration have a 14% higher pregnancy rate.

Adequate nutrition can positively impact the number of calves born in the first 21 days, 205-day adjusted weaning weight and the ability to calve unassisted and breed back. Co-products are not a complete source of nutrients but with appropriate supplementation the cost of protein and energy can be reduced and poor quality roughage can be fed.

Proper feeding does not need to be complicated or expensive provided a program is developed under the guidance of a competent professional nutritionist. Requirements for protein, energy fat and minerals must be met to achieve optimal performance from herds. Projections for biofuel production suggest continued availability of byproducts to supplement diets for cows well into the future. Feeding co-products will enhance long-term ranch profitability.

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