Think of a cow’s nutritional needs according to her place in the cycle.
Feed is both a principal cost and a principal factor in reproductive performance. This relationship dictates the fundamental goal of cowherd nutrition programs—achieving an optimal reproductive rate for cows.
A challenge of feeding beef cows is that their nutritional requirements change dramatically during the year based on their BCS, size, pregnancy, lactation status and environmental conditions. Because of these stages, it is common to divide the cow year into four periods.
Period 1, nursing cow. She needs to get bred; her nutrient requirements will be the greatest in this period.
Period 2, cow bred and lactating. At this point, pregnancy demands are small, and peak milk is past.
Period 3, mid-gestation. At this point, the calf is weaned; this is usually the period with the lowest nutrient requirements and a prime opportunity to increase cow BCS.
Period 4, 2 to 3 months prior to calving; during this time fetal growth rate is at its highest and the cow should be in adequate flesh. Having cows underfed in period 4 can result in lighter calf birth weights, lower calf survival, lower milk production, lower calf growth and delayed estrus—which translates to later calving next year and lower weaning weights.
As cow weight increases, the nutritional requirement for energy and protein increases. BCS has gained considerable favor because it has been demonstrated that reproduction in beef cows is greatly influenced by body fatness. The goal should be to have cows calve in good body condition and avoid significant loss in condition between calving and the start of the breeding season.
Milk production places tremendous demands on cows. Peak milk usually occurs by 60 to 80 days after calving which is right before the breeding season. The nutrients spent on milk production means high-producing cows tend to get pulled down physically, which will make it more likely that she will breed later in the season. Feeding thin, high-producing cows more feed prior to reaching peak milk tends to cause them to milk more rather than to gain weight.
The age of the animal influences nutritional requirements: a young cow is still growing. Most cows found open are 2- and 3-year-olds. Young cows should be gaining about half a pound per day. If these young cows fail to rebreed, it is an indication that feeding was inadequate to the animal’s maintenance, growth and milk production nutrient requirements. If possible, young cows along with old or thin cows, should be separated and fed a more dense diet than mature cows.
Winter feeding guidelines
Quality and quantity of forage available are the major factors influencing intake. Intake is probably most influenced by the quality of forage with intake decreasing dramatically as quality decreases. When forage quality is low or average, forage intake is increased with protein supplementation but not with energy supplementation. This increase in intake caused by adequate protein supplementation, coupled with maintenance of forage digestibility, means that the total daily energy status of the cow is increased. This is a win-win situation. If protein is adequate, cows will consume about 1.8 percent of their bodyweight as forage dry matter (less if they are fat, more if they are thin). Usually energy is the most commonly deficient nutrient in beef cow diets, but protein often represents the largest out-ofpocket expense. Proper protein supplementation of poor quality forages will increase forage intake. Increased forage intake meets the cow additional energy intake. Thus, to maximize profitability, it is essential to optimize protein supplementation. Inadequate dietary protein results in low forage intake and digestibility, resulting in much poorer performance. If you are feeding hay, budget at least 2 percent of body weight as hay DM per head per day.
Mineral supplementation calcium, phosphorus, magnesium and salt are often fed as the macro minerals. Cattle on a plant-based diet will always be sodium short, and they are likely to be calcium short unless there are legumes in the forage. Phosphorous will be short in dormant-mature forages, but may be adequate in young forage. You should supplement with magnesium in the early spring to prevent grass tetany, especially on cool-season forages such as fescue and wheat pasture. Supplementation should be started about three weeks prior to initiation of grazing. The recommended intake of magnesium can be achieved by feeding Ricochet mineral all the time or Hi-Mag or Mag-ADE meal. Ca, P, Mg, and salt are required at significant amounts and are major considerations in diet formulation.
When evaluating cow herd feeding programs, bear in mind that a high percentage of problems with poor reproduction and low weaning weights can be directly attributed to inadequate energy, protein feeding or both. This is much more common and likely than vitamin or mineral deficiencies. First verify energy and protein feeding, then evaluate vitamins and minerals.