Nutritional Needs of the Beef Cow

April, 2019
 Jonael Bosques, UF/IFAS Extension Hardee County, Wauchula

Nutrition plays a key role to ensure that each cow gives birth to a strong, healthy calf and rebreeds every year within approximately 80 days of year. An inadequate nutrition program may result in a low percent calf crop, late calving and decreased weaning weights.

When calves are sold at weaning, more emphasis is needed on management and nutrition to increase weights than when calves are carried over and sold as yearling feeders. Earlier birth dates, a short calving period and a higher milking cow all help produce heavier weaning weights on calves. These also require more feed and emphasize the need for a well-planned nutritional program.

Stage of Production

A cow's nutrient needs are largely determined by her stage of production. A production cycle, or cow year, can be divided into four stages: (1) calving to breeding--70-80 days; (2) breeding to weaning--approximately 120 days; (3) mid-gestation--approximately 100 days; (4) late gestation--60-70 days.

 

Early lactation/calving to breeding - This is the most critical period with regard to a cow's nutritional requirements. She is producing milk at her highest level 3-4 weeks postpartum through breeding, while her reproductive system is recovering from her past pregnancy. Cows that lose weight during this period have lower first-service conception rates than cows that gain some weight. Lower first-service conception rates result in longer calving intervals. A cow's weight loss at this time also decreases the weaning weight of the calf.

Breeding to weaning – Milk production declines during this period, lessening a cow's nutritional requirements. She generally gains weight (with summer grass), and the most serious effect of poor feed is lowered weaning weights. Nutrition rarely affects the developing fetus at this stage.

Mid-gestation with the calf weaned – In this stage a cow requires little other than enough feed to maintain her own weight. Requirements for the fetus are small in terms of nutrient requirements. Cows can use lower quality feeds during this period without affecting production.

Late gestation – The total liveweight of a pregnant cow in late gestation includes the maternal weight plus the fetus and associated components (membranes and fluids). During this period, the fetus gains approximately one pound per day. Thus, a cow must gain nearly a pound a day just to maintain her own maternal weight during late gestation. Cows losing weight during this period take longer to start cycling after calving and may have lowered conception rates. If supplementation is needed, it should begin during this period to ensure the birth of strong, healthy calves and early rebreeding of cows.

 

Age of Cows

Nutrient requirements of young developing heifers differ from those of older cows, so they should be handled separately. Because they are still growing, yearling heifers need higher percentages of protein, energy, calcium, and phosphorus in their diets than older cows, both before and after calving. Further, older cows may force younger heifers away from feed, which is another reason for separation. Yearling heifers, two-year-old bred heifers and thin older bred cows might be handled together to avoid numerous small groups of cattle.

Nutrient Requirements

Nutrient requirements during various production stages of heifers calving as two-year-olds and cows calving as three-year-olds and older are shown in table 1. To decide on what to feed or if supplement is needed, one must estimate the dry matter intake as well as the quality of forage.

Table 1.  Nutrient requirements of heifers and cows (percentage of ration dry matter; Guide B-213 NMSU Publication)
Parameters Early Lactation/Calving to Breeding Mid Pregnancy Late Pregnancy
Heifers-calving as 2's
Protein (%) 9.5-10.8 8.0 8.5-9.0
TDN (%) 63-65 48-52 52-58
Calcium (%) 0.34 0.20 0.20-.23
Phosphorous (%) 0.24 0.20 0.20-..23
Cows-calving as 3's or older
Protein (%) 9.6 7.0 7.9
TDN (%) 56-58 48-49 50.54
Calcium (%) 0.28 0.18 0.26
Phosphorous (%) 0.22 0.18 0.21

Samples of stored forage such as hay can be analyzed, making it possible to estimate supplemental needs accurately. Unfortunately, no single range supplement will do the job for all ranchers all the time. Supplemental programs should be varied, depending on the class, condition, age and reproductive status of the animal to be fed as well as the quality and quantity of forage available. In different years, different supplements may be needed in varying amounts.

Cow-calf herds are grazed yearlong in South Central Florida. Some general guides for supplementing these herds are based on current understanding of nutritional requirements, previous experience, and research for developing programs. These guides, which you can use in developing your supplement program, include the following:

 

Energy Nutrition

  • Winter range and low-quality harvested forages usually provide adequate energy for bred mature cows, if the range or forages are available in adequate quantities. Under these conditions, protein is more likely to be deficient with yearling heifers likely to be deficient in both energy and protein, generally needing to be supplemented.
  • In pastures subject to drought or overgrazing, energy is most likely to be deficient. A supplement containing more energy relative to the protein should be fed, e.g., a 20% protein "high energy" supplement.
  • Feeding plant protein supplements with low-quality forage may improve energy nutrition of the cow more than feeding small amounts of grain. Small amounts of grain without protein supplementation tend to cause decreased forage digestibility and intake.

 

Protein Nutrition

  • Protein is needed to provide adequate nitrogen for the functioning of rumen bacteria. Protein supplementation can increase the digestibility and intake of low-quality forages, so that the energy provided in these forages is used more efficiently.
  • Protein supplements, including legume hay, appear to be as effective when fed two or three times weekly as when fed daily. When these supplements are fed less frequently, timid cows are more likely to get their share, because greater amounts are fed at one time and "boss" cows have fewer opportunities to consume more than their share of the feed. Also, cows may graze more when supplemented at 2- and 3-day intervals. 

 

Mineral Nutrition

  • Supplemental phosphorus can be provided in a protein supplement, a mineral supplement, or a salt-mineral mix. A commercial mineral mix should contain a minimum of 6% percent phosphorous and should be fed with no other salt available to insure adequate phosphorus intake. Phosphorus sources include dicalcium phosphate and defluorinated rock phosphate, all offering similar amounts of phosphorus for beef cattle.
  • Trace minerals are seldom needed but are usually supplied at low cost in commercial supplements.
  • Calcium:phosphorus ratios are not the problem in beef cattle as in non-ruminants. Normally there is little to worry about unless the calcium-to-phosphorus ratio exceeds 3:1 in a supplement (three times as much calcium as phosphorus). Amounts are listed on the feed tag.

 

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