Nutrition and Management: Finishing Cull Cows

This is a fact sheet from the Nutrition and Management section of the Alberta Feedlot Management Guide,Second Edition published September 2000. The 1200 page guide is available for purchase on CD-ROM.

Take Home Message

• Mature cows are usually culled from the beef herd in October through December or in the spring after failing to deliver a live calf.
• These cows are often in moderate to thin body condition.
• Finishing cull cows on feedlot diets offers considerable potential to improve carcass composition and net return if cows are young, healthy and thin and if cow prices are rising.

• The market that the cows are destined for will influence the level of fat on the cows and the subsequent feeding program.
• Length of feeding period will be determined by the target market. For Canadian markets, the optimum feeding period will often be less than 60 days. After 60 days, cows will become overfat, gains decline and carcass grade could be discounted. For American markets the fat allowances are higher resulting in a longer feeding period.
• Young cows gain faster than older cows and can grade youthful. Age verfied cows offer greater flexibility that cows of unknown age.
• Carcasses from cows less than 3.5 years old (may have 2nd or 3rd pair of permanent teeth) may grade youthful. Changes in carcass weight and grade result in youthful carcasses having a considerably higher profit potential than those that can only grade D.
• Finishing cull cows makes economic sense when grain prices are low and slaughter cow prices are high. Feed is the largest component of the cost of gain. Processing, yardage, interest and vet costs account for most of the remainder. Poor feed conversions keep cost of gain expensive.
• Young feeder cows trade at a premium price to older cows. A high portion of the potential gain in carcass value may already be priced into the purchase cost.
• Cows may be pregnant.
• Death loss could be 2.0% which is considerably higher than the typical 0.5% for feeders and there may be condemned carcasses. Reasons relate to previous health problems and acidosis in the feedlot.

Cull cows can experience normal and/or catch-up growth. Normal growth is as occurs in the young when there is an increase in stature and an increase in the soft tissues such as muscle, fat and internal organs. Catch-up growth is an increase in the muscle tissue and fat but no skeletal growth. It occurs when an animal’s diet is changed from being restricted to being adequate for gain. Most of the catch-up growth will occur in the first 70 days after reintroduction of an adequate diet. In one trial, cull cow weight gain was 51% fat, 14% protein and 35% moisture. It illustrates that deposition of protein occurs much slower than fat for cull cows. Two and three year old thin cull cows will experience both normal and catch-up growth while thin cows greater than five years old have simple catch-up growth. The catch-up growth of older cows is comprised of low amounts of fat initially, but fat deposition increases rapidly as maximum size is attained. Fat cover increases with increasing time spent on feed. Among all age groups, older cows have the greatest rate of fat deposition. This differentiation in growth can explain why in some trials younger cows have daily gain up to 24 percent higher than older cows.

Intake

At weaning, cull range cows are often depleted of body fat. These thin ‘shell’ cows can have a tremendous appetite and will eat from 2.5 to almost 4 percent of their body weight daily for the first few weeks on feed. An 1100 pound cow could consume up to 41 pounds of dry matter, but might average closer to 30 to 35 pounds daily. Fleshy or young cows would tend to consume less than thin or older cows of similar weight. Intake increases as energy density of the diet increases. Their large appetites compared to other classes of feedlot cattle make them more susceptible to digestive problems such as bloat and acidosis.

Diet Mix

The most rapid and efficient gains are obtained with high grain diets (Table 1). Cull cows can be fed increasing grain levels over a two to three week period until consuming an 80% concentrate and 20% roughage diet (dry matter basis).

Coarsely ground or rolled barley, oats or wheat are suitable grains for cull cows. Barley is usually preferred because of it’s availability, high energy content and competitive price. Include wheat at levels less than 50 percent of the total grain intake when its availability and price is suitable.

Either cereal or grass-legume roughage as silage or hay are suitable for cull cows. However, silage is the preferred roughage since it allows for grains and supplements to be mixed giving a total mixed ration. Silage is highly palatable making it easier to start cattle on feed, and feeding is easily mechanized.

Protein supplementation is probably not required for barley based diets. However if required, feed a commercial protein or feedlot supplement containing 18 to 22% levels of equivalent protein from a non protein nitrogen source (urea). These supplements also supply vitamins ADE, calcium, trace minerals, and registered feed additives such as Rumensin®, Bovatec® or Posistac®.

Daily Gain

Feedlot performance will decrease as time on feed and body condition increases. Thin healthy cows have excellent gains, perhaps greater than 4.0 pounds per day on high grain diets, especially for the first 30 to 50 days. The 21 trials reported in Table 1 where cull cows were fed from 59 to 116 days. Overall gains were 3.2 ± 0.6 pounds daily. This level of gain occurred in thin cows exhibiting catch-up growth. Fleshier cows would not gain as fast. Older cows gain slower than cows 4 years old and younger.

Feed Conversion

Feed conversion will range from 8 to 10 pounds dry matter per pound gain but can be higher. Feed conversion will be from 7 to 8 pounds of dry matter per pound of gain in the early stages of the feeding period. Several trials report feed conversions greater than 12.5 during later stages. There is no reported effect of breed on gain or feed conversion for cull cows. The high weight gain early in the feeding period is partially due to an increase in gut fill. The poorer feed conversion at later stages is likely the result of a higher maintenance requirement due to increased weight and an increased portion of the weight gain as fat.

Treatments

Cull range cows have shown a 4 to 11 percent growth response to implants. Internal parasite control may be required and is likely economical. Follow manufacturers directions explicitly when using any products and ensure that withdrawal times, if any, are observed.

Dressing Percent

Cull range cows in thin condition will have dressing percentages from 45 to 48%. After an 8 to 10 week high energy feeding program, expect a 2% to 6% increase in dressing percentage, peaking at 11 weeks on a feedlot diet.

Table 1. Summary of Cull Cow Feeding Trials.

Grain Level (DM)	Days on Feed	ADG lb/day	Feed to Gain	Backfat Deposition mm/day	Source
80%	87	3.1	10.8	0.04	21
63%	84	3.1	7.8	0.15	72
69%	62	2.2	12.8	NA	11
80%	62	3.5	8.8	NA	11
20%	103	2.5	9.7	0.07	13
40%	87	3.4	8.4	0.09	13
80%	63	4.5	5.2	0.14	12
80%	108	4.2	6.2	0.11	12
40%	57	2.8	12	0.11	12
80%	58	3.5	7.7	0.12	12
90%	56	3.5	7.7	NA	43
90%	56	2.8	9.7	NA	44
90%	0-56	4.0	6.9	0.11 overall	4
90%	57-112	2.5	12.8		4
705	68	3.0	8.5	0.04	55
70%	68	3.3	8.3	0.04	56
85%	50	2.8	9.0	0.05	10
85%	77	3.0	9.2	0.09	10
85%	105	3.1	9.1	0.1	10
90%	50	3.0	10.4	0.06	3
84%	63	3.1	9.6	0.02	8

¹ Feed to Gain was 19.7:1 for days 63 to 87
² Feed to Gain was 6.9:1 for first 56 and 12.5:1 for last 28 days
³ three and four year old cows and ⁴ six years and older cows
⁵ young Holstein and ⁶ old Holstein cows

Changes in Carcass Composition and Grading

Feedlot finishing cull cows will improve carcass weight, tenderness, ribeye area, marbling and fat colour. The increase in ribeye area occurs predominantly in younger cows and may be related to an increase in muscle fibre diameter in older cows. Marbling increases occur between days 28 to 56 on high grain diets with smaller changes throughout the remainder of the feeding period. Carcass composition changes may be related more to days on feed than actual grain level fed. Fat colour becomes whiter with increasing days on a high grain diet. The half life of beta-carotene is about 30 days. This implies that beta-carotene in the fat would be nearly gone by 60 days for animals on a high grain diet and as such the fat should be white.

Maturity or age is important since there is a direct relationship between tenderness and maturity. Maturity is determined by condition of the bone (Table 2). The split between youthful and mature carcasses occurs somewhere near 30 months of age (Table 3).

Table 2. Key Distinctions of Youthful and Mature Carcass.

	Youthful	Mature
Cartilaginous caps on thoracic vertebrae	no more than half ossified	more than half ossified
Lumbar vertebrae	have evidence of cartilage or at least a red line on the tips	no evidence of cartilage or of a red line on the tips
Spinous processes	porous and red when split	hard, white and flinty when split
Sternum	shows distinct divisions	shows advanced ossification

Adapted from: (6)

Table 3. Distribution of Carcasses after 50 days on feed by Dental Classification at Feedlot Entry.

Age Classification	Youthful	Mature
- # head	39	54
Permanent Teeth
- 1st pair	93%	7%
- 2nd pair	50%	50%
- 3rd pair	55%	45%
- 4th pair	6%	94%

Source: (3).
Classification based on (6).

Strategies for Feeding Cull Cows

Table 4 suggests some possible strategies for deciding which cull cows to feed and for how long. The teeth could be examined in open cows or cows less than 150 days pregnant to determine cow age. Pregnant young cows (up to 3rd pair of teeth) could be aborted as would thin older cows. Based on age, cows could be fed to A1/A2 finish, for 50 to 60 days or not at all. Cows greater than 150 days pregnant could be resold.

Table 4. Strategies for Feeding Cull Cows (3).

Pregnancy Status	Pairs of Teeth, Condition	Possible Strategy
Open	1st pair	feed to A1/A2 finish (60 to 100 days)
	2nd or 3rd pair	feed 50 to 60 days
	4th pair, thin condition	feed 50 to 60 days
	4th pair, fleshy	resell, live or on rail
<150 days pregnant	1st pair	abort, feed to A1/A2 finish (60 to 100 days)
	2nd or 3rd pair	abort, feed 50 to 60 days
	4th pair, thin condition	abort, feed 50 to 60 days
	4th pair, fleshy	resell, live or on rail
>150 days pregnant		resell as bred cow

Summary

Feeding cull cows can be profitable but there are risks. The decision to feed cull cows must consider cow prices, seasonal price direction, and feed costs. Purchasing young cows which have the potential for an improvement in carcass grade will likely show the highest return. Caution is in order. The potential increased carcass value of seemingly youthful cows may already be capitalized in the purchase price. A 60 day feeding program which adds 200 pounds to cull cows may be profitable but an extra 20 days on feed could produce a costlier overfat D4 cow and a lower net return (see Marketing Cull Cows). Perhaps 40% of mature cattle will grade D4 (overfat) after as few as 50 days on feed. There is virtually no profit potential for cattle grading D4.

References

1. Beerwinkle,D.L. et al. 1979. Muscle fiber enlargement in realimentated cull range cows. Proc. West. Sect. Am. Soc. Anim. Sci. 30:99-101.
2. Burgwald, L.A. et al. 1992. Influence of energy source on production and carcass characteristics in cull beef cows fed concentrate diets. Proc. West. Sec. Am. Soc. Anim. Sci. 43:510-514.
3. Graham, W.C. 1993. Unpublished data from Lakeside Feeders Ltd., Box 800, Brooks, AB.
4. Graham, W.C. and M.A. Price. 1982. Feedlot performance and carcass composition of culled cows of different ages. Can. J. Anim. Sci. 62:845-854.
5. Jones, S.D.M. and G.K. MacLeod. 1981. The feedlot performance and carcass composition of young and mature cull Holstein cows. Can. J. Anim. Sci. 61:593-599.
6. Livestock Carcass Grading Regulations. 1992 Agriculture and Agri-Food Canada.
7. Matulis, R.J. et al. 1987. Growth and carcass characteristics of cull cows after different times-on-feed. J. Anim. Sci. 65:669-674.
8. Price, M.A. and R.T. Berg. 1981. On the consequences and economics of feeding grain ad libitum to culled beef cows. Can. J. Anim. Sci. 61:105-111.
9. Price, M.A. and M. Makarechian. 1982. The influence of zeranol of feedlot performance and carcass traits of culled cows and heifers. Can. J. Anim. Sci. 62:739-744.
10. Pritchard, R.H., and P.T. Burg. 1993. Feedlot performance and carcass traits of cull cows fed for slaughter. South Dakota Beef Report. 93-20:101-107.
11. Riley, J. 1978. Feeding cull beef cows in feedlots. Kansas State Univ., Cattle Feeder’s Day Report. pp69-71.
12. Swingle, R.S. et al. 1979. Realimentation of cull range cow. I. Effect of final body condition and dietary energy level on rate, efficiency and composition of gains. J. Anim. Sci. 48:913-918.
13. Wooten, R.A. et al. 1979. Realimentation of cull range cow. 2. Changes in carcass traits. J. Anim. Sci. 48:823-830.