September is calving season for many fall-calving herds. Nutritional management of fall-calving cows is a little different than spring-calving herds throughout the production cycle. Peak energy, measured as total digestible nutrients (TDN), and protein requirements occur early in lactation at about 1 to 3 months after calving (Figure 1). For spring-calving cows, the calving season is typically aligned with peak energy and protein requirements occurring at the time pastures green up such that the young tender grass with high protein and digestibility can meet those nutrient requirements. For fall-calving cows, the ability of pasture to meet peak energy and protein requirements is highly dependent upon the forage species. Cool-season forages such as fescue regrow in the fall when temperatures begin to cool down providing highly nutritious grass to meet the requirements of the cow during this time. However, warm-season forages are slowing growth as temperatures decline and becoming dormant having much lower nutritive value and less ability to meet the nutrient requirement of cows in early lactation. But, stockpiled bermudagrass or native grass with protein supplementation can effectively meet the nutrient requirements of fall-calving cows. And planting cool-season annual forages can easily meet the nutrient requirements of lactating beef cows, and can even be used as a supplement to warm-season pasture by limiting the time cows graze the annuals each day.
Fall-calving cows have a couple of advantages. One advantage is the climate which is typically dry and cool, which does not increase maintenance requirements like cold and wet conditions in the spring. The second advantage is that fall-calving cows came through the summer grazing months without a nursing calf and are usually in very good body condition; 6 or better. Greater body condition at calving allows these cows to lose some condition without detrimental effects on reproductive performance. The breeding season for fall-calving cows is usually late November through December such that cows are pregnant before bad winter weather. Pregnant cows are unlikely to lose a pregnancy due to poor body condition, which allows fall-calving cows to lose some condition through the winter. This works financially because cows will be able to regain lost condition inexpensively on pasture next summer. It is not advisable to let spring-calving cows lose condition through the winter leading up to calving as it is not economically feasible to regain condition between calving and breeding seasons.
A possible disadvantage of fall-calving cows is that some feeds available in the fall of the year may not be suitable. As displayed in Figure 1, the energy requirement is much greater than the protein requirement and is expensive to provide because of the tonnage necessary. Thus, feedstuffs with lower digestibility may not be good options. For example, corn stalks can readily meet the nutrient requirements of spring calving cows after weaning, but may not work for fall-calving cows except for a few weeks early on when cows are consuming leaves, husks, and down ears. Other feeds such as ammoniated wheat-straw will require significant energy supplementation to meet energy requirements of cows in lactation and high levels of ammonia intake may have negative effects on reproductive performance.
Fall-calving cows can be especially challenging in a drought. Forage production was less than usually so cows are thinner than usual at calving and do not have the surplus fat to lose condition through early lactation and breeding. Additionally, alternative forages such as crop residue or wheat straw will require substantial supplemental grains and byproducts to meet nutrient requirements. Meeting nutrient requirements during the time between calving and breeding is critical if cows are only in moderate body condition because the loss in pregnancy rate will impact the ranch for several years to come. Planting cool-season annuals is an option, but requires fall rains to get the crop established, and if not established early in the fall, forage growth will be too little for winter grazing.
Plan on feeding a considerable amount of supplement to fall-calving cows during fall and winter in drought years. Conventional feedstuffs are likely to be expensive as demand is high and supply may be low. Look for alternative feeds such as failed crops, spent grains from local breweries, fruit and vegetable waste from local supermarkets, etc. Any untapped waste stream that provides rumen-digestible, safe feedstuff that is less expensive per unit of energy (TDN) will be advantageous during drought.
As we move into late summer and early fall, we begin think about weaning time. Weaning can be a stressful event and there are some techniques such as fence line weaning to reduce that stress, but the focus of our discussion today is feeding those weaned calves. Stressed calves and calves that are not used to a feed bunk do not readily consume feed. Getting those calves on feed is critical requiring a good diet and proper feed management. A starter diet should include feeds that calves are familiar with such as hay and highly palatable feeds such as dried distiller’s grains. Feeds such as corn silage are great for growing cattle but can turn calves off from eating because it has a different smell and taste. Silage can be incorporated slowly after calves are eating well. Feed needs to be delivered in a manner that encourages feed intake. A good way to do this is to provide feed in an open bunk perpendicular to the fence line. An open bunk does not require calves to put their head into or through a stanchion that might hinder feed consumption. Placing the bunk perpendicular to the fence line requires bawling calves to walk into the bunk when pacing the fence.
One important consideration for backgrounding calves is to assess feed resources. Home grown forages and grains are typically used, but purchased feeds can also be used. An assessment of the quantity and quality of feeds needs to be completed to know whether enough feeds are available for the entire length of the backgrounding period and to formulate diet to meet the production goals. Feeding calves to achieve the correct weight at the correct time is critical for marketing and profitability. There are a couple of methods to formulating diets for backgrounding calves. One method is to formulate a diet with greater than 50% forage which is fed to appetite. This method requires less management and equipment. This method can be implemented with a predetermined amount of grain feed in bunk and free-choice hay, but may have better results as a totally mixed ration fed in a bunk. The second method is to formulate a diet with less than 50% forage which is fed in limited amounts. The advantage of this method is that high energy feeds, which are typically less expensive on a per unit of energy basis, are used reducing the cost of gain. However, this method requires more intensive management in that diet formulation needs to be more precise and correct feeding management in the form of bunk space and accurate feed delivery. Implementation of the limit-feeding method necessitates the use of a totally mixed ration and feed mixing equipment.
Backgrounding fall-weaned calves instead of selling calves at weaning can have a couple of drawbacks that can be overcome with time. Calves will likely lose weight during the first few days after weaning due to stress and reduced feed intake. Getting calves to regain the lost weight will have a high cost of gain requiring a backgrounding period long enough to reduce the overall cost of gain. Additionally, as the fall run of calves gets into full swing, the price of calves will decrease requiring calves to gain enough weight to more than offset the reduced price. Thus, deciding on the proper market time and weight are necessary to profit from backgrounding, which will influence the diet and feeding program necessary to meet those goals.
As we move into the heat of summer, forage plants begin to reach maturity which means that the amount of lignin deposited in the plant cell wall increases and the amount of protein decreases. This is a continual process as the plant matures, but when the plant begins to put up seed heads is usually when forage digestibility begins to decline, although this can be forage species dependent. Lignin is not readily digested by rumen bacteria, and it also inhibits digestion of the rest of the plant cell wall. Additionally, the decrease in protein concentration becomes limiting for growth of rumen bacteria which decreases their ability to digest plant material. The increase in lignin and decrease in protein combine to reduce forage digestibility which in turn decreases the amount of forage the animal can consume. This becomes a double-edged sword in that the animal does not get as much nutrition from each bite and cannot eat as much.
It is impossible to remove the lignin once it is deposited in the plant cell wall. The only management strategy is to slow down the rate of plant maturation by frequent grazing. To accomplish this effect, cattle must be moved to a new paddock every day which is not practical for many ranches. Also, there is discrepancy as to whether frequent grazing/rest periods has the same effect with all forage species in all regions of the country.
Even though maintaining low lignin concentration of forages is not always practical, increasing the protein supply to rumen bacteria is beneficial and practical. Digestibility of forage can be improved with protein supplementation when forages mature in late summer. Previous research at Kansas State University indicates a 13% improvement in digestibility of native prairie hay with protein supplementation. Available protein sources that work well are soybean meal and cottonseed meal that provide large amounts rumen degradable protein meaning that this protein is available to the rumen bacteria. Other feedstuffs such as distiller’s grains are lower in rumen degradable protein and higher in energy and are better suited when both energy and protein need to supplemented.
Protein supplementation can be easily implemented in many ranch situations due to the ability of the ruminant animal to recycle nitrogen within the body. Because of this ability to recycle nitrogen back to the rumen, beef cows and stocker calves can be supplemented with a high protein feed every 3 to 6 days rather than daily with similar benefits in forage digestion. Be sure to monitor the maturity of forage plants in pastures over the next few weeks to determine the appropriate time to begin protein supplementation. Work with your veterinarian or county extension agent to determine the appropriate time and amount of protein supplement.