The effect of body size on feed efficiency has been the subject of research for several years. Evidence was presented from some of the early research that body weight is unrelated to feed efficiency. Recent research has also shown that current recommended net energy requirements, such as those by the National Research Council, for growing and finishing beef cattle are valid for various sizes and types of beef animals. Large-bodied cattle gaining at a faster rate require more feed and should be fed ro heavier weights to reach best market grade

Costello, W. J.

Embry, L. B.

Swan, W. S.

English

Public Research Access Institutional Repository and Information Exchange

South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSouth Dakota Cattle Feeders Field Day Proceedingsand Research Reports, 1975 Animal Science Reports1975Energy Level in Ration, Market Weight and Typesof CattleL. B. EmbrySouth Dakota State UniversityW. J. CostelloW. S. SwanFollow this and additional works at: http://openprairie.sdstate.edu/sd_cattlefeed_1975Part of the Animal Sciences CommonsThis Report is brought to you for free and open access by the Animal Science Reports at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in South Dakota Cattle Feeders Field Day Proceedings and Research Reports,1975 by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For moreinformation, please contact michael.biondo@sdstate.edu.Recommended CitationEmbry, L. B.; Costello, W. J.; and Swan, W. S., "Energy Level in Ration, Market Weight and Types of Cattle" (1975). South DakotaCattle Feeders Field Day Proceedings and Research Reports, 1975. Paper 5.http://openprairie.sdstate.edu/sd_cattlefeed_1975/5South Dakota State University Brookings, South Dakota Department of Animal Science Agricultural Experiment Station A. S. Series 75-23 Energy Level in Ration, Market Weight and Types of Cattle L. B. Embry, w. J. Costello and W. S. Swan The effect of body size on feed efficiency has been the subject of research for several years. Evidence was presented from some of the early research that body weight is unrelated to feed efficiency. Recent research has also shown that current recommended net energy requirements, such as those by the National Research Council, for growing and finishing beef cattle are valid for various sizes and types of beef animals. Large-bodied cattle gaining at a faster rate require more feed and should be fed to heavier weights to reach best market grade. Animal performance and time needed to reach various market weights can be changed by the amount of roughages and concentrates in rations and by length of time of feeding high-roughage and high-concentrate rations in a two-phase system involving a growing, or backgrounding, phase and a high-concentrate finishing phase. More information is needed on the comparative performance of cattle that vary in potential adult size under systems of feeding using rations containing various levels of roughages and concentrates or using varying intervals of high-roughage and high-concentrate feeding. Such information would be useful in selecting rations and feeding systems that result in optimum weight gains and best use of feeds to reach desirable market weight for size of cattle involved. The experiment reported here was designed to compare two groups of cattle with different potential adult size when fed rations which varied in energy contents and when marketed after different times of finishing. Angus x Hereford steers were used to represent one size and Charolais x Hereford the other. Procedures Specific objectives of the experiment were: 1. To compare high-energy and low-energy diets as to feedlot performance and carcass characteristics of feedlot steers. 2. To determine effects of final market weight on feedlot performance and carcass characteristics of steers fed under two dietary regimens. 3. To determine the influence of potential mature body size of cattle on feedlot performance and carcass characteristics under variable conditions as to energy concentration of diets and market weights of cattle. 17 - 2 -Cattle and Feeds Sixteen pens each with eight steers were used in the experiment. Variation in potential adult size was represented by a Angus x Hereford (AH) group and a Charolais x Hereford (CH) group (8 pens of 8 each for each breed group). The steers were purchased in the spring after having been wintered in a good thrifty condition. They were purchased over a period of about 1 month. Upon arrival and prior to the beginning of the experiment, they were fed a ration of 5 lb. corn grain and a full feed of alfalfa-brome hay or haylage. All cattle were vaccinated for prevention of blackleg and implanced with 36 mg zeranol shortly after beginning of the experiment. Allotment to the experiment was on basis of weight within breed group. A high-energy diet (2 lb. roughage air-dry matter, ADM) or a low-energy diet (10 lb. roughage ADM) was offered to four pens of steers within each breed group. Two of the four pens were fed chopped alf alf a-brome hay and two pens were fed alf alfa-brome from the same source with water added and stored as reconstituted haylage. Corn grain was fed to appetite with each level of roughage. It was pur­chased as dry grain. Water was added and the corn stored as reconstituted high-moisture grain (about 27% moisture). Considerable cracking of the grain occurred when blowing into the silo. No further processing was used for the grain. A soybean meal-corn supplement (22% protein) was fed at 2 lb. per head daily with the low level of forage (estimate about 11% protein in ration). No supplemental protein was considered necessary with the higher level of forage. However, a supplement of corn with added minerals, vitamin A and chlortetra­cycline was fed at 2 lb. per head daily. Ingredient composition of supplements are shown in table 1. The cattle on the higher level of forage were started at the 10 lb. level (ADM) and 2 lb. of supplement with corn grain at 5 lb. per head. The corn grain was increased by 1 lb. per head daily to a full feed. The cattle on the lower level of forage were started on feed at the same levels as above. The forage was reduced by 1 lb. (ADM) per head daily to the 2 lb. level. Corn was increased by 1 lb. daily to a full feed. After obtaining a full feed, corn was fed to appetite with constant levels of forage and supplement. Feeding was once daily in outside, paved pens. Weight Groups The cattle within each breed and energy level group were marketed at two final weights. The AH group was used to set these points. It was planned to market weight group 1 when the average feedlot weight of the AH steers averaged about 1050 pounds. The planned feedlot weight for marketing AH steers in weight group 2 was about 1200 pounds. CH steers in the two weight groups were marketed at the same time as the AH steers. 18 - 3 -The two weight groups for each breed and energy level were fed in the same pens until time of marketing for those in weight group 1. At this time four of the eight steers were marketed. The remaining steers in each pen were continued on the same feeding program for the weight group 2 phase of the experiment. Carcass data were obtained upon slaughter. Results Results of the experiment are shown in table 2. The cattle in weight group 2 which received the lower energy ration and fed for the longest time were weighed on January 7 after 236 days on experiment. There was a severe blizzard on January 10 and 11. The cattle were fed in the usual manner on January 10 but feeding was not possible the next day. For the following two days, the cattle were full-fed alfalfa-brome hay and shipped to market on January 14. The decision to·market as soon as the cattle could be shipped following the blizzard was made in view of the closeness of the January 7 weight to the planned market weight and amount of shrink expected from the weather conditions. Because of these conditions, it was considered advisable to base the weight gain on carcass weights with the final live weight calculated on basis of a constant dressing percent. A yield of 62% was used. Weight gain and feed efficiency data for all treatment groups were calculated on this basis. Weight Gain Average weight of the AH steers was 563 lb. at the beginning of the experi­ment in comparison to 619 lb. for CH steers. Selection was made to obtain steers which appeared to have similar backgrounding treatment rather than similar weight between breed groups. The cattle in weight group 1 and fed the higher energy ration were marketed after 146 days. Average weight of AH steers was 1008 lb. with an average daily gain of 3. 06 pounds. CH steers marketed at this time had gained 0. 29 lb. (9.5%) more daily. Weight gains were reduced by feeding to the heavier market weight with the high-energy ration. Average weight of the AH steers when marketed was 1197 lb. and the average daily gain was 2. 92 pounds. This represents a reduction over the total days of 4. 6% in comparison to weight group 1. However, assuming similar gains for the two weight groups up to point of marketing weight group 1, the reduction thereafter would amount to 14.1%. CH steers showed similar reductions in rate of gain when fed to the heavier weight as did AH steers. There appeared to be no difference between the two breed groups in this charac­teristic. Lower weight gains were encountered with the lower energy rations for each breed group of steers. Within breed group, the weight gain reduction from weight group 1 to weight group 2 was about the same as for the higher energy ration (approximately 4 to 5% for each group) . Reductions in weight gain with the lower energy ration amounted to 13. 7 and 12. 7%, respectively, for the two weight groups of AH steers. For CH steers, the reductions amounted to 19. 1 and 19 - 4 -20. 2%, respectively, with the lower energy ration at the two weight groups. The advantage in weight gain for CH steers over AH steers with the high energy ration was not apparent with the lower energy ration at either weight group. Feed Data CH steers consumed more feed than did AH steers. While there was a greater intake of feed with the lower energy ration, the amount of increase by each breed group was similar. Feed intake decreased when fed to the heavier weights with no major differences between type of ration or breed groups of cattle. Higher rates of gain for CH steers associated with the higher intake of feed resulted in only small differences between the two breed groups in feed efficiency with the higher energy ration. Even though weight gains were lower when fed to the heavier weights, the reduction in feed intake resulted in similar feed efficiency for the two weight groups. Lower rates of gain with higher feed intakes with the lower energy ration resulted in pronounced increases in feed requirements for both groups of cattle at each market weight. While there was a slight increase in overall feed require­ments at the heavier weights, it was about the same in magnitude (2.6%) for each group of steers. Carcass Characteristics AH steers graded higher than CH steers. Differences were greater for the higher energy ration and for the longer time on feed. The differences in carcass grading were primarily a reflection of amount of marbling. AH steers had more marbling in all breed group comparisons within type of rations and days fed. However, response in amount of marbling to energy level of rations and days fed was similar for the two breed groups, except for CH steers fed the lower energy ration. Amount of kidney fat as percent of carcass weight was similar for the two groups of cattle. It was slightly higher for each weight group when fed the lower energy ration. Fat thick ness showed only small effects from rations or days fed. However, AH steers had the most fat covering. CH steers had larger rib eyes but carcasses were heavier when marketed after the same number of days on feed. When fed the higher energy ration, the heavier market weight resulted in larger rib eyes. This effect was not evident with the lower energy ration with either breed group of cattle. Summary Effects of energy level of rations and market weight on feedlot performance and carcass characteristics were studied with two groups of cattle which varied in potential mature size, Angus x Hereford (AH) and Charolais x Hereford (CH). Comparisons were made between rations with 2 lb. and 10 lb. of forage (ADM) with 2 lb. of supplement and corn grain fed to appetite. Feeding periods were 146, 174, -216 and 236 days for various rations and market weights with cattle from each breed group marketed at each time. 20 - 5 -Results of the experiment show an advantage on basis of weight gain for the larger type cattle when fed the higher energy ration (2 lb. forage ADM). While there was a reduction in rate of gain with the lower energy ration ( 10 lb. forage AD}n, there were only small differences between two breed groups. It would appear that large-bodied cattle capable of making a fast rate of gain benefit more from high-energy rations. The larger cattle consumed more feed resulting in only small differences in feed efficiency between the two breed groups. Feed requirements were increased more for the lower energy ration when fed to the heavier weights. However, the lower energy ration resulted in rather small savings in total con­centrates per unit of forage on basis of feed efficiency for weights of cattle in this experiment. AH steers had more marbling and a higher carcass grade but with a smaller rib eye and more fat covering. Marbling and carcass grade were improved at the heavier marketing weight by the higher energy ration with these effects being slightly more evident with AH steers. Table 1. Ingredient Composition of Supplements Low energy diet High energy diet Ingredient ( 10 lb. roughage ADM) (2 lb. roughage ADM) % % Ground corn grain 94.58 44.58 Soybean meal (44% protein) 40.00 TM salt 3.00 3.00 Limestone 9.00 Disodium phosphate 2.00 Potassium chloride 3.00 Vitamin A premix 0.07 0.07 (10,000 IU/lb. supplement) Aureomycin-10 0.35 0.35 (35 mg CTC/lb. supplement) 21 N N Table 2. Feedlot Performance and Carcass Characteristics as Affected by Energy Content of Diets, Market Weight and Types of Cattle High energy diet Low energy diet AxH CxH AxH CxH Wt. 1 Wt. 2 Wt. 1 Wt. 2 Wt • 1 Wt • 2 Wt • 1 Wt. 2 Nwnber of animals Nwnber of days fed Init. shrunk wt., lb. Adj. final wt., lb. Avg. daily gain, lb. Avg. daily ration, lb. Hay or haylage Com grain Supplement Total Feed/100 lb. gain, lb. Hay or hay lage Com grain Supplement Total Hot carcass wt., lb. Conf ormationa Marblingb a Carcass grade Colorc d Firmness Percent kidney fat Rib eye area, sq. in. Fat thickness, in. 16 146 562 1008 3.06 3.20 20.17 1.99 25.36 105 660 65 830 625 21.5 6.9 20.6 5.0 5.3 3.0 10.83 0.61 15 216 566 1197 2.92 2.99 19. 37 2.00 24.36 103 663 69 835 742 22.4 8.5 22.0 4.8 6.0 3.1 11.45 1.02 16 146 621 1111 3.35 3.20 22 .37 1.99 27.56 96 668 59 823 689 20.9 5.3 19.0 4.7 5.1 2.9 11.97 0.43 14 216 616 1310 3.21 2.98 21.26 2.00 26.24 93 662 62 817 812 21. 7 6.6 20.2 4.3 5.8 3.0 13.12 0.65 16 174 561 1021 2.64 13.52 14.62 1.99 30.13 523 559 76 1158 633 20.4 6.3 19.7 5.2 5.8 3.4 11.38 0.55 16 236 564 1166 2.55 13.20 14.85 1.99 30.04 526 584 78 1188 723 21.5 7.8 20.8 4.7 6.3 3.6 10.95 0.94 15 174 621 1092 2. 71 13.52 15.52 1.99 31.03 519 577 74 1170 677 20.l 5.7 19.4 4.6 5.3 3.3 12.38 0.48 8prime = 23, Choice • 20, Good= 17. Graded to one-third grade. bModerately abundant = 9, slightly abundant = 8, moderate= 7, modest= 6, small= 5. �Higher number represents darker meat. Higher number represents firmer meat. 16 236 618 1224 2.56 13.22 15.43 1.99 30.64 520 603 78 1201 756 20.4 5.8 19.5 4.4 5.6 3.6 12.15 0.64 CJ\ 

Energy Level in Ration, Market Weight and Types of Cattle

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Energy Level in Ration, Market Weight and Types of Cattle

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