Calving can be a rewarding time, with each new birth helping justify the time, effort, and financial inputs invested in the cowherd. But unacceptably high – and possibly preventable – death loss among calves can be economically devastating.
Nationwide, calf death losses run an average of 5-7%, with similar patterns emerging in studies done in Colorado, Kansas, Montana, and other states. USDA numbers estimate the total number of preweaning deaths near 2.7 million per year, with a value of nearly one billion dollars annually. One study showed that these ‘typical’ losses equated to taking 35 pounds off of each calf sold at weaning. The greatest concern, of course, is a jump in the death rate; a herd with a serious scouring problem, for example, can lose half their calf crop.
Dystocia, or calving difficulty, probably accounts for half of all preweaning deaths. Calves with hard or prolonged births can suffer from hypoxia (lack of oxygen), acidosis, musculo-skeletal injury, and hypothermia. If calves don’t die from the immediate stress, they may succumb later due to brain damage or impaired immune status. Scours (diarrhea) can be caused by various bacterial, viral, and protozoal infections, and even those animals that survive will carry the cost of treatment and reduced lifetime performance. Concerns over hypothermia naturally vary by geographic region, but a wet calf can become dangerously chilled even with fairly moderate temperatures. Cold stress not only reduces suckling activity, but also can delay immunoglobulin absorption from colostrum, and reduce cellular immunity.
Research suggests that calf death losses are greater with some breeds of cattle, in old (> 11 years) cows and heifers, with very small or very large birth weights, and in any situation that increases the incidence of dystocia. Beyond the long-term issues of breeding management and culling, opportunities to minimize death losses fall into three main areas: reducing dystocia, maximizing calf vigor, and enhancing immune response.
The common thread here is obviously cowherd nutrition, especially during gestation. Cows on inadequate feeding programs prior to calving have offspring that are less vigorous, slower to stabilize body temperature, and slower to nurse. These calves have impaired cold tolerance, due to a combination of reduced thermoneutral metabolic rates and smaller deposits of brown adipose tissue.
Low-protein gestation diets have been linked to “weak calf syndrome.” Research studies that have specifically looked at inadequate protein supplies during mid- to late-pregnancy have found reductions in the amount of colostrum produced, impaired calf vigor, reductions in calf heat production, decreased absorption of some immunoglobulins from the colostrum, and failure of the calf’s immune system to develop properly. Work done at the U.S. Meat Animal Research Center demonstrated that calves with low serum immunoglobulins were 1.5 times more likely to get sick, and 2.4 times more likely to die, before they were weaned. In another study (Wittum and Perino, 1995), calves with inadequate serum IgG were 6.4 times more likely to die by 28 days of age, and 5.4 times more likely to die before weaning.
Other scientists have examined the impact of low-energy diets during pregnancy. Besides the increase in calving difficulty seen with thin cows (see the December 2002 CattleSense), specific studies have seen an 11% drop in calf body heat production (Colorado), a 19% increase in the incidence of scours (Wyoming) and a drop in survival rate from 100% to 71%.
Cow body condition is frequently used as an indicator of previous nutrition. The following table (from Odde et al., 1986) shows the impact of condition score at calving on calf vigor, colostrum production, and immune function. A similar study (Holland et al., 1987) compared adequate and inadequate levels of gestation-diet protein. Cows receiving proper nutrition produced 2683 ml of colostrum, and had calves that stood in 66 minutes; inadequately fed cows only produced 1931 ml of colostrum, and their calves didn’t stand for an average of 97.4 minutes.
Mineral and vitamin nutrition is also important to calf health. One study showed that calves which died from scours received colostrum that had less vitamin A, vitamin E, copper, and zinc than the colostrum produced by cows with healthy calves. Another report demonstrated that calves which were susceptible to E. coli scours had lower body concentrations of copper, zinc, manganese, and vitamin A. Copper is of special concern, since milk is a poor source of this mineral. It is critical that enough copper be available for storage during fetal development to meet the calf’s early needs. Cowherd deficiencies of selenium and vitamin E have also been tied to mastitis, weak calf syndrome, scouring, pneumonia, depressed immunity, and impaired cold tolerance.
IN SUMMARY -- KEYS TO MINIMIZING CALF LOSSES:
- HEALTH PROGRAM: Maximize disease resistance with a vaccination program and management that guarantees an adequate supply of high-quality colostrum for every calf. Limit exposure to pathogens.
- ENVIRONMENT: Provide areas that are well-drained and sheltered
- GOOD COWHERD NUTRITION. Maintaining cow body condition and properly developing heifers are the first key to healthy, vigorous calves. Use a supplement program to ensure adequate supplies of protein, energy, minerals, and vitamins. Consider feeding low levels of fat during late pregnancy.
Source: Dr. Cathy Bandyk, Quality Liquid Feeds