During any given production year on the ranch, cows and heifers are faced with nutritional and environmental stressors. They have periods of high and low nutritional demands. Knowing the stress periods that can result in nutrient deficiencies is where you, the rancher, must manage to your and your ranch’s best ability to help the cow or heifer meet these nutritional challenges.
How well do you know your ranch? Does it have any advantages or shortcomings that you can utilize or need to augment to affordably meet any nutritional challenges? Some examples of advantages could be wet meadows, irrigated pasture, dryland annuals, windbreaks, proximity to crop residue, etc.
What can you afford? Realizing that you cannot always afford to meet a cow’s nutrient requirements will help you in your nutritional plan. For example, put body condition on your cows when their energy requirements are the lowest (Figure 1), and let the cow use that body condition as an energy source when you cannot afford to meet her requirements. Feed costs are a major expense for any cow-calf operation.
As such, knowing what type of supplement is needed, when it is needed and how to compare supplements based on nutrient content will help you make better decisions on needed supplement purchases.
Another important question is, “How does your management affect the cows?” Do you have dystocia problems? Are you managing your cow herd so cows are rebreeding every year? Are you managing the genetics of your herd? Are your pastures/forages sustaining from year to year?
A final question to ask is, “How does your management of the dam affect the calf?” When calves are born, are they vigorous and able to get up and suckle the dam? Are cows producing sufficient colostrum? Is there sickness in your calves? What are your weaning weights? Questions like these can help in your management to ensure you have healthy calves and cows that have a calf every year.
Body condition scores (BCS) describe the relative fatness of a cow through the use of a 9-point scale. Body condition scoring is an effective management tool to evaluate the nutritional status of the herd. For a spring-calving herd, the key times to BCS your gestating females are late summer (early wean if needed), fall, weaning, 45 days after weaning, and 90 days before calving (your last opportunity to economically put condition on your cows/heifers).
The most economical time to put condition on thin cows is after weaning. Ninety days before calving is the last opportunity to put condition on cows economically. If possible, sort thin and adequate condition scores into different feeding groups. This will help develop a feeding plan that will maintain cows in adequate body condition or provide needed weight gain for thin cows prior to and through the breeding season.
Having an inventory of your feed on hand for both quantity and quality will help you with your feeding and supplement decisions. Testing your feedstuffs will enable you to have a more strategic feeding program, and you will be able to prioritize your quality feedstuffs to younger and thinner females.
Looking at Figure 1, we see that the cow’s highest energy requirement is at peak milk production, about 60 days after calving. This coincides with the breeding season. She has calved, is producing milk, is recovering from calving and is getting ready for breeding. To help prepare your mature cows for this, having them in a BCS of at least 5 at calving is recommended. The heifer is still growing, and it is recommended that she be in a BCS of 6 at calving.
Separating heifers from mature cows should be done at least three weeks prior to calving. First-calf heifers decrease their daily dry matter intakes (DMI) by 17% in the three weeks prior to calving. Feeding an energy- and protein-dense diet to heifers is necessary to compensate for this reduced intake at calving.
In late gestation, the energy requirements of a mature 1,200-pound cow are relatively low (9-11 pounds total digestible nutrients or TDN per day, 2 pounds crude protein per day). As that cow grazes dormant range or low-quality forages, supplementation of 2-2.5 pounds of a 20% to 25% crude protein (CP) source would meet the cow’s maintenance demands at this stage of production.
As a mature cow enters calving and lactation, her protein and energy requirements increase. A lactating cow at peak lactation (60-80 days postpartum) has an energy demand of 15-16 pounds of TDN per day. There is a shift in the cow’s first limiting nutrient from protein to energy.
Body condition of beef cows that calve in the spring influences productivity of the herd. As body condition of a cow increases at calving for March-calving cows, the interval from calving to the first estrus, known as the postpartum anestrous interval, is reduced (see Table 1). Thin (BCS 4 or less) cows are slower to rebreed after calving compared to cows in moderate body condition.
As you consider the nutrition requirements of your cows and heifers, keep in mind that their requirements change depending on their stage of production. Using body condition scoring will help you evaluate the nutritional status of your herd. Keep in mind that how you manage these nutritional requirements can not only have cow effects, but also calf effects.
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