Can We Develop a Cow-less Cowherd? Beef Production without Mature Cows
A beef production system is being studied that eliminates the mature cow herd. Nulliparous heifers are bred with sexed semen enriched to >90% X-sperm, so most heifers replace themselves with a heifer calf. Weaning will occur at about 100 days of age after which the dam is fattened for ~2 mo and slaughtered at 28-30 mo of age.
Research objectives are:
1. Determine profitability by evaluating capital requirements, expenses, and income.
2. Evaluate ways of initiating such a program, e.g. starting with weaned heifer calves, open heifers, or bred heifers.
3. Determine if carcasses produced are of a quality that avoids market discounts.
There is no cow herd to feed year-round, and all cattle are growing. In traditional cow/calf systems, ~50% of consumed feed energy goes to metabolic maintenance of mature cows with no accretion in meat. The other ~50% is for calf/replacement-heifer maintenance, growth, and fattening, and for cow pregnancy and lactation. In the new system all cattle are growing, so a high percentage of feed energy goes to growth. The net result is a significant decreases in feed required per pound of beef produced, manure, greenhouse gas production, and excretion of nitrogen and phosphorus.
Fringe benefits include: eliminating low pregnancy rates in first-calf heifers that are lactating and still growing; minimizing health problems such as cancer eye, foot and leg ailments, mastitis, etc. more prevalent in older cows; almost eliminating bull calves needing castration; and decreased generation interval. Fringe costs include an increase in dystocia if all calving is from heifers, expected to be minor, because heifer calves average 2 kg lighter than bull calves at birth, and easy calving AI sires will be used. Early weaning requires increased management, and heifers gain weight less efficiently than steers, which can be compensated by using anabolic implants. This system is not entirely self-sustaining because of: imperfect semen sexing; inevitable deaths; and non-pregnancy or late-pregnancy of some heifers. Thus, to maintain herd numbers, 25-30% of heifers need to be replaced annually from outside of the system. Fringe benefits appear to outweigh fringe costs, but the main advantage is that more beef can be produced with given feed resources.
Keywords: sexed semen, efficiency, heifer beef