*Dr. Philipe Moriel is an assistant professor and Luis Felipe Artioli is a graduate student with the North Carolina State University department of animal science. To expedite answers to questions concerning this column, please direct inquiries to Feedstuffs, Bottom Line of Nutrition, 7900 International Dr., Suite 650, Bloomington, Minn. 55425, or email [email protected].

DECREASING the frequency of supplementation to reduce costs associated with labor, equipment and fuel is not a recent topic in the grazing beef cattle industry.

Numerous studies have evaluated the effects of providing supplements infrequently -- for example, three or five times weekly -- instead of every day to beef cattle fed forage-based diets (Kunkle et al., 2000; Cooke et al., 2007a, 2007b, 2008; Moriel et al., 2012; Drewnoski et al., 2014). However, before deciding to decrease the frequency of supplementation, producers need to be aware of the implications of this decision because the results reported in the literature are not consistent.

The outcome of reducing the supplementation frequency on growth performance depends on several factors, particularly the type of nutrient provided (for example, protein or energy). In the case of protein-based supplements, it was shown that supplementing beef cattle as infrequently as once a week instead of daily did not affect growth performance, forage intake or digestibility (Kunkle et al., 2000).

In contrast, decreasing the frequency of energy supplementation can be detrimental to beef cattle performance, depending on forage quality and type of energy supplement provided. When cattle were consuming low-quality forages, decreasing the frequency of supplementation (low- or high-starch supplements) had negative effects on forage intake and growth performance (Kunkle et al., 2000; Cooke et al., 2007a, 2008).

For instance, beef heifers consuming low-quality bahiagrass -- 54% total digestible nutrients (TDN) and 9% crude protein (CP) -- and offered daily supplementation of fibrous byproducts -- wheat middlings, soybean hulls, cottonseed meal and molasses -- had a greater average daily gain (ADG) of 0.90 lb. versus 0.73 lb. per day, respectively, and achieved puberty sooner than heifers offered the same supplement three times per week (Cooke et al., 2008).

On the other hand, decreasing the supplementation frequency of low-starch supplements when beef cattle are consuming medium- to high-quality forages did not impair the growth performance of beef heifers and steers (Moriel et al., 2012; Drewnoski et al., 2014), but this had detrimental effects on puberty achievement of beef heifers (Cooke et al., 2008; Moriel et al., 2012).

For example, daily supplementation of a soybean hull-based concentrate to Brangus crossbred heifers consuming low-quality stargrass hay (50% TDN and 8% CP) or medium-quality bermudagrass hay (52% TDN and 12% CP) did not affect ADG but increased the percentage (40% versus 20%) of heifers cycling at the beginning of the breeding season (Moriel et al., 2012).

The reason for the greater percentage of pubertal heifers when supplements were provided daily instead of three times weekly can be associated with less fluctuation of the synthesis and release of hormones and metabolites (such as insulin and glucose) associated with reproduction and energy metabolism. Thus, although the ADG of beef steers and heifers may not be affected by reducing the frequency of energy supplementation, the reproductive performance of beef heifers may be impaired.

It is possible that the outcome of reducing the frequency of energy supplementation for cattle consuming medium- to high-quality forages might also depend on the life stage of the animal.

Our hypothesis was that the immune response of recently weaned calves could be affected by reducing the frequency of energy supplementation. The period immediately following weaning is one of the most stressful events in a calf's life. Hence, decreasing the frequency of supplementation, regardless of forage quality and supplement type, might increase the stress response to weaning and decrease the growth performance and immunity of recently weaned, stressed beef calves.

Therefore, our goals were to evaluate the effects of reducing the frequency of energy supplementation (three times weekly versus daily) during preconditioning on the growth performance, intake and immune response of beef calves.

Briefly, 24 Angus-crossbred steers (480 lb. of bodyweight and 210 days of age) were weaned, provided with free-choice access to ground tall fescue hay (17% CP and 58% TDN) and supplemented with a pellet mix of 50% soybean hulls and 50% corn gluten feed for 42 days.

Supplements were offered three times weekly -- 11.5 lb. of supplement on every Monday, Wednesday and Friday (S3) -- or daily -- 5 lb. of supplement every day (S7) -- resulting in the same amount of supplement being fed each week. Calves were vaccinated using the Select-Vac protocol from Zoetis on days 14 and 28 after weaning.

Results

In this study, ADG was 0.6 lb. per day lower for S3 steers compared to S7 steers (Table).

In contrast, Drewnoski et al. (2014) reported that yearling Angus or Angus x Simmental cross steers (630 lb. of bodyweight) had similar ADG when they consumed medium-quality tall fescue hay (10% CP and 57% TDN) and were supplemented daily or every other day with a mix of 50% soybean hulls and 50% corn gluten feed.

Hence, the reason for the differences in growth performance between those studies may be associated with the life stage of those calves, i.e., recently weaned versus yearling calves. Steers in our study were in a crucial period of their productive life -- i.e., a stressful period immediately following weaning -- and did not respond positively to reducing the frequency of supplementation.

In our study, feed efficiency did not differ statistically but was numerically lower when the frequency of supplementation was reduced. Also, S3 steers consumed 54 lb. less total dry matter compared to S7 steers, which is a result of the lower hay dry matter intake, since both treatments received the same weekly supplement offer (35 lb. of supplement per steer per week).

Therefore, the lower hay intake of steers supplemented three times weekly led to lower total energy and protein intake, which partially explains the reduced ADG compared to steers supplemented daily.

Immune response

We also analyzed one of several acute-phase proteins called haptoglobin (an indicator of inflammatory response after stress or immunological challenge) and observed that S3 steers had greater plasma haptoglobin concentrations (0.78 versus 0.55 + 0.041 mg/mL; P = 0.002) compared to S7 steers. This response supports the hypothesis that reducing the frequency of supplementation enhances the stress response of weaned calves.

In addition, we analyzed the percentage of calves responding to vaccination (seroconversion) and the production of antibody titers against bovine viral diarrhea virus type 1b (BVDV-1b). Although the percentage of calves responding to the vaccination did not differ between treatments (P = 0.26), S7 steers had greater (P = 0.03) antibody titers against BVDV-1b than S3 steers (Figure).

Further studies need to be conducted to evaluate if this greater antibody titer production can increase the immune protection of those calves. However, it is possible that the immune response of weaned steers receiving daily energy supplementation was enhanced, which might result in greater immune competency against a pathogen invasion.

The reason for the greater antibody response is not known, but it could be associated with less fluctuation on nutrient intake and synthesis of hormones and metabolites. Hence, our data indicate that the constant nutrient intake and synthesis of hormones and metabolites due to daily energy supplementation seems to benefit not only puberty achievement (Cooke et al., 2008; Moriel et al., 2012) but also the immune response of weaned calves.

The Bottom Line

In summary, offering a low-starch energy supplement daily instead of three times weekly to recently weaned beef steers consuming medium-quality forages reduced the daily variation in nutrient intake and enhanced the growth performance and antibody production against BVDV-1b. Therefore, these data indicate that producers should not reduce the frequency of energy supplementation to beef steers during the preconditioning period.

References

Cooke, R.F., J.D. Arthington, D.B. Araujo, G.C. Lamb and A.D. Ealy. 2008. Effects of supplementation frequency on performance, reproductive and metabolic responses of Brahman-crossbred females. J. Anim. Sci. 86:2296-2309.

Cooke, R.F., J.D. Arthington, C.R. Staples and X. Qiu. 2007b. Effects of supplement type and feeding frequency on performance and physiological responses of yearling Brahman-crossbred steers. Prof. Anim. Sci. 23:476-481.

Cooke, R.F., J.D. Arthington, C.R. Staples, W.W. Thatcher and G.C. Lamb. 2007a. Effects of supplement type on performance, reproductive and physiological responses of Brahman-crossbred females. J. Anim. Sci. 85:2564-2574.

Drewnoski, M.E., G.B. Huntington and M.H. Poore. 2014. Reduced supplementation frequency increased insulin-like growth factor 1 in beef steers fed medium quality hay and supplemented with a soybean hull and corn gluten feed blend. J. Anim. Sci. 92:2546-2553

Kunkle, W.E., J.T. Johns, M.H. Poore and D.B. Herd. 2000. Designing supplementation programs for beef cattle fed forage-based diets. Proceedings of American Society of Animal Science. Accessed Oct. 27, 2007, at www.asas.org/jas/symposia/proceedings/0912.pdf.

Moriel, P., R.F. Cooke, D.W. Bohnert, J.M.B. Vendramini and J.D. Arthington. 2012. Effects of energy supplementation frequency and forage quality on performance, reproductive and physiological responses of replacement beef heifers?. J. Anim. Sci. 90:2371-2380.

Volume:87 Issue:27