Extension

The use of roughages in traditional growing programs promotes dry matter (DM) intake and minimizes metabolic upsets.¹ However, greater intake of roughages decreases feed conversion and elevates feed cost.² By the same token, increasing energy density or modifying energy sources in the diet, namely via nonstructural carbohydrates, increases the risk for digestive disorders including ruminal acidosis and liver abscesses.³ Limit-feeding a high-energy diet to growing cattle offers attractive opportunities in some situations for enhanced growth performance by improving feed efficiency and health detection, decreasing cost of gain, and easing transitions to finishing diets.⁴

 

Kansas State University researchers conducted three experiments to compare two growing diet strategies; a high-roughage diet fed for ad libitum intake vs. a high-energy limit-fed diet.⁵ The objectives of experiments 1 and 2 were to evaluate the effects of growing strategy on growth performance and behavior during the growing period and to determine if growing strategy influenced subsequent feedlot performance and carcass characteristics. The objective of experiment 3 was to measure apparent diet digestibility and ruminal fermentation characteristics of heifers fed a highroughage diet for ad libitum intake or limit-fed a high-energy diet.

 

In experiment 1, 409 crossbred heifers (initial body weight = 615 lb) in 32 pens were used in a randomized block design. Heifers were fed one of two dietary treatments: a total mixed ration with 45 Mcal net energy for gain (NEg)/cwt dry matter (DM) fed ad libitum or 60 Mcal NEg/cwt DM limitfed at 85% of intake of heifers fed the high-roughage diet in an 84-day growing and receiving period. Both diets contained 40% wet corn gluten feed (Sweet Bran; Cargill Animal Nutrition) on a DM basis. The cattle were fed once daily at 7:00 am. Bunks were visually assessed each morning at 6:00 am, and estimated orts were recorded. Limit-fed pens always consumed their daily allotment, requiring 3 to 4 hours to reach an empty bunk.

 

In experiment 2, 370 crossbred heifers (initial BW = 496 lb) in 16 pens were used in a randomized block design and were fed the same diets used in Experiment 1 except the limit-fed treatment was fed at 2.2% of BW daily on a DM basis. Heifers were fed once daily at 7:00 am. Bunks were visually observed, and orts were estimated at 6:30 am. The treatment diets were fed for 84 days for 2 blocks and for 91 days for 2 blocks.

 

For experiments 1 and 2, treatment integrity was maintained through the finishing phase where cattle were fed a common diet. Cattle were sorted by BW into heavy and light groups prior to finishing, with light cattle fed longer than heavy cattle to reach similar harvest BW.

 

In experiment 3, eight ruminally cannulated heifers (average BW = 673 lb) were used in a 2-period cross-over design and fed treatments from experiment 1 to assess digestibility and ruminal fermentation characteristics.

 

The effect of ad libitum high-roughage or limit-fed high-energy diets in the backgrounding phase on performance are presented in Table 1 for both Experiments 1 and 2. Gain:feed ratio was 47% and 35% greater (P < 0.01) in experiments 1 and 2, respectively, for limit-fed heifers compared with ad libitum fed high roughage heifers. In experiment 1, the better efficiency for limit fed heifers was the result of 15% greater (P < 0.01) ADG and 22% lower (P < 0.01) DM intake. In Experiment 2, ADG was 15% lower (P < 0.01) and DM intake was 38% lower (P < 0.01) for limit-fed heifers than ad libitum fed heifers. These authors noted that the differences in treatment responses in Experiments 1 and 2 can be attributed to the different amounts of the high energy limit-fed ration that were offered. In both experiments during the backgrounding phase, heifers exhibited few clinical signs of morbidity, and mortality was low.

 

Experiment 1

 

Experiment 2

^aHigh roughage diet formulated to contain 45 Mca/l NEg/cwt fed ad libitum in both experiments. Highenergy diet formulated to contain 60 Mcal NEg/cwt and limit fed at 85% of high roughage treatment DM intake in Experiment 1 and limit fed at 2.2% of BW on a DM basis in Experiment 2.

^bTreatment end date was day 84 for 2 blocks, and day 91 for 2 blocks. Adapted from Scilacci et al., 2024.

 

 

In Experiment 1, during the finishing phase there was an effect of growing diet (P < 0.01) for initial BW and ADG, with limit-fed heifers having greater initial BW than ad-libitum fed heifers, which was due to treatment differences that occurred in the growing phase. Limit-fed heifers had 5.5% better (P = 0.03) ADG compared to ad libitum cattle. No main effects (P ≥ 0.21) of growing diet were detected for days on feed, final BW, morbidity, or mortality. In Experiment 2, initial BW tended (P = 0.06) to be greater for limit-fed heifers. No differences (P ≥ 0.53) between growing diets were observed for days on feed, final BW, or ADG. Morbidity was 15.5% greater (P < 0.01) for limit-fed heifers than ad-libitum heifers. Mortality did not differ between feed treatments.

 

In Experiment 1, carcasses of cattle that had been fed limit fed had greater (P < 0.01) backfat than those of cattle fed ad-libitum, but more (P= 0.02) ad-libitum carcasses graded USDA Prime than limit-fed carcasses (10.0 vs. 5.1%). There was a tendency (P = 0.07) for a greater percentage of limit-fed carcasses to grade USDA Choice than ad-libitum carcasses (89.3 vs. 84.2%). Liver abscess prevalence at harvest was similar between heifers fed a high-roughage or high-energy diet during the growing phase. In Experiment 2, no effects (P > 0.52) of growing diet were observed for any carcass characteristics.

 

In Experiment 3, apparent total-tract DM and organic matter digestibilities were greater (P < 0.01) for limit-fed heifers than ad-libitum fed heifers.

 

These researchers concluded “that overall, limit-feeding during the growing phase had minimal impacts on subsequent growth performance during the finishing phase and carcass characteristics”. In addition, limit-feeding high-energy diets based on corn and fermentable fiber during the growing phase did not increase prevalence of liver abscesses. The greater gain efficiency and diet digestibility in cattle limit-fed high-energy diets used in this study could provide beef producers with a strategy to boost operational productivity and reduce manure output.

 

In these experiments, two separate approaches to limit-feeding growing heifers were evaluated. These authors noted that limit-feeding at 85% of ad libitum is likely not practical on a commercial scale as it would require a group of cattle fed for ad libitum intake to determine limit-fed feed deliveries. In experiment 2, limit-fed heifers were fed at 2.2% of BW daily (DM basis). To accomplish this, weekly pen weights were measured which also would not be practical on a commercial scale. They noted that a more reasonable approach to limit-feeding growing cattle may be to determine BWs at the start of the feeding period, feed at a designated % of BW, and use predicted weight gains to increase feed delivery over time.

---

¹ Lofgreen, G. P., J. R. Dunbar, D. G. Addis, and J. G. Clark. 1975. Energy level in starting rations for calves subjected to marketing and shipping stress. J. Anim. Sci. 41:1256–1265. Available at: https://doi.org/10.2527/jas1975.4151256x.

 

² Richeson, J. T., K. L. Samuelson, and D. J. Tomczak. 2019. Beef species-ruminant nutrition cactus symposium: energy and roughage levels in cattle receiving diets and impacts on health, performance, and immune responses. J. Anim. Sci. 97:3596–3604. Available at: https://doi.org/10.1093/jas/skz159.

 

³ Owens, F. N., D. S. Secrist, W. J. Hill, and D. R. Gill. 1998. Acidosis in cattle: a review. J. Anim. Sci. 76:275–286. Available at: https://doi.org/10.2527/1998.761275x.

 

⁴ Galyean, M. L., E. E. Hatfield, and T. L. Stanton. 1999. Restricted and programmed feeding of beef cattle—definitions, application, and research results. Prof. Anim. Sci. 15:1–6. Available at: https://doi.org/10.15232/S1080-7446(15)31715-0.

 

⁵ Scilacci, M. A., E. C. Titgemeyer, Z. M. Duncan, T. J. Spore, S. P. Montgomery, T. G. O’Quinn, A. J. Tarpoff, W. R. Hollenbeck, and D. A. Blasi. 2024. Effect of traditional roughage-based or limit-fed, high-energy diets on growth performance and digestion in newly received growing cattle and subsequent implications on feedlot growth performance and carcass characteristics. Transl. Anim. Sci. 8. Available at: https://doi.org/10.1093/tas/txae082.