Developing a nutritional program that meets the needs of beef cattle throughout the production cycle and facilitates a successful calving season and a return to cyclicity before the next breeding season takes an understanding of how cattle partition nutrients and the factors that impact their overall nutritional requirements. Typically, the beef production cycle can be broken down into four general stages: calving to breeding, breeding to weaning, after weaning and pre-calving. Cattle utilize the nutrients they consume based on specific biological priorities: maintenance, growth, lactation then reproduction. Due to reproduction being last on the list, it is often the first production-related factor impacted by inadequate nutrition.
Although the period between calving and breeding is one of the critical times to manage cattle nutrition requirements, grazing forages post-weaning through the fall and winter offer their own unique challenges. After weaning, cattle are no longer lactating, resulting in their most modest nutrient requirements in the production cycle. Thus, this stage of production represents the best time of the year to have the greatest impact on cattle condition through nutritional management. However, most grazed forages have hit maturity and are often dormant at this time. Dormant forage is high in fiber and deficient in protein (less than 8% crude protein) and likely doesn’t meet cattle nutrient requirements. Therefore, grazing low-quality dormant forage will likely result in decreased cattle performance even when cattle no longer have the nutritional demands for lactation.
Providing protein supplements to grazing beef cattle during times of low forage quality can improve animal performance. Traditionally, concentrate feeds (cereal grains) were used to supplement energy on dormant forage diets; however, it has been found that grain-based supplements can have negative impacts on the digestibility and dietary consumption of low-quality forage (5% to 8% crude protein). This is mainly because dormant forages are typically deficient in protein and high in fiber, which physically limits dietary consumption. Protein supplementation helps by stimulating the cattle’s protein-starved rumen microbial communities and thereby enhancing digestibility and increasing dietary consumption to meet nutritional requirements with high-fiber, low-quality forages.
In general, when consuming low-quality dormant forage, mature cattle will require 0.5 to 1 pound of supplemental protein (approximately 2.5 to 5 pounds per head per day of a 20% crude protein supplement). However, growing heifers require a high concentration of protein in the diet due to a lower intake and their requirements for growth. With proper protein supplementation, cattle can maintain and potentially gain weight and body condition while grazing dormant forages in the fall and into winter. Thus, grazing stockpiled forages in the fall and into winter can be a great strategy to reduce the hay/feeding cost, as long as there is an adequate protein supplementation program in place.
However, gestation in the latter part of the third trimester can have a major impact on cattle nutrient requirements, due to the majority of fetal growth happening the last 60 days prior to calving. The increase in nutrient requirements to support fetal growth requires an increase in feed and supplement management to maintain an optimal body condition score during this period. It is well established that cattle entering calving and breeding at body condition scores below 5, on a scale of 1 to 9, have substantially decreased first-service conception rates, especially for high-producing cattle and 2- to 3-year-olds that still have individual growth requirements. This is because cattle with inadequate body condition at calving or those that have lost condition post-calving take longer to recover from the stress of calving (90 days or more). This of course results in lower first-service conception rates, a greater likelihood of open cows, an extended breeding season, an extended calving season the following year and greater variability in calf weaning rates. Cows with a body condition score of 5 to 6 are generally considered to be in ideal condition for rebreeding. Managing nutrition to achieve and maintain this target body condition score prior to calving is crucial and may involve adjustments to feeding strategies based on individual cow needs and forage availability.
Nutritional management plays a central role in promoting the health, productivity and reproductive success of beef cattle. Understanding the specific nutritional requirements of cattle can aid in utilizing low-quality forages with supplementation, allowing producers to optimize herd performance and profitability. Continued monitoring and adaptation to changing forage conditions are key to ensuring cattle receive the nutrients they need to be successful while consuming low-quality forages.
