It's critical for replacement heifer development to be low cost, without sacrificing performance. Heifers should be managed to reach puberty early, conceive early in the breeding season and calve unassisted. Recommended guidelines for breeding heifers generally fall between 60-66% of their mature body weight (BW).
University of Nebraska researchers conducted a three-year study using spring-born heifers to determine the effects of developing heifers to 55-60% of their mature BW at breeding. A concurrent study measured summer-born heifers to examine the effects of breeding heifers with the mature cow herd or one month earlier on reproduction and calf production variables.
Pregnancy rates through the fourth pregnancy were measured. Spring-born heifers reached 53% or 58% of their mature BW at breeding and had similar reproduction and first-calf production between the two groups. Calving difficulty with the second calf was greater with the heifers developed to 58% of their mature BW. Feed costs were $22/heifer less for heifers developed to 53% of their mature BW.
Summer-born, first-calf heifers calving in June had less calving difficulty than those calving in May, but calf birth weights were similar. Breeding summer-born heifers one month before the rest of the cows didn't influence pregnancy rates over three calf crops, but first-calf adjusted weaning weights and average daily gains were greater for calves born earlier.
Researchers determined that developing heifers to 53% of mature BW didn't adversely affect reproduction or calf production traits compared with developing them to 58% mature BW, and it decreased development costs. Breeding summer-born heifers one month earlier than the rest of the cow herd increased heifer development costs, increased calving difficulty and improved calf performance, but had no effect on pregnancy rates (Funston, et al., 2004 J. Anim. Sci. 82:3094-3099).
Energy supplementation for beef cows may be necessary if the nutrient content is low in forages or if availability is scarce.
University of Montana researchers conducted a study to determine the effects of feeding nonstructural carbohydrate (NSC) supplements, such as cereal grains, on intake and digestibility of low-quality forages. The study measured digestion in 28 yearling heifers, and a two-year winter grazing trial studied 60 crossbred cows.
The treatments included: 1) control, no supplement; 2) 0.32 kg of NSC supplements; 3) 0.64 kg of NSC supplements; 4) 0.96 kg of NSC supplements.
In the first experiment, heifers were individually fed hay containing 5.5% crude protein (CP) and their respective supplements for 28 days. In experiment 2, cows were individually fed supplements on alternate days and grazed in rangeland pasture.
Researchers found supplements containing NSC improved forage digestion and intake when heifers consumed forage deficient in CP relative to energy by supplying additional nitrogen to ruminant microbes. The same supplements resulted in a decrease in forage intake and digestibility by cows grazing native range that had adequate protein relative to energy (Bowman et al., 2004 J. Anim. Sci. 82:2724-2733).
South Dakota State University research shows raw, frost-damaged soybeans should be limited to less than 14% of cattle diet dry matter (DM) to avoid problems with consuming too much oil or enzyme inhibitors.
Poor growing conditions in 2004 caused some soybeans to be damaged by frost or immaturity at harvest. This resulted in green soybeans that were either refused or discounted at local elevators.
While green soybeans aren't desirable for consumption in the consumer market because of pigmentation, they can be used effectively as livestock diet.
Whole soybeans are lower in protein and higher in fat than soybean meal. They also contain a high amount of oil (about 18%), which limits the amount that cattle can intake. The fats and oil tend to reduce fiber digestibility and animal performance when fed at high levels. Keeping the levels at or below 14% will help avoid problems.
Whole soybeans don't need to be ground or rolled prior to feeding, but it may be desirable to process them in some way to facilitate proper mixing and minimize sorting. Researchers also recommend a nutrient analysis of the frost-damaged or immature soybeans before balancing rations or feeding.
— Greg Lardy, Ranch Hand Newsletter, November 2004