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Previous issues of the BEEF Cattle letter
Issue # 512
November 15, 2006
Hitting the Right Target Weight is Critical to Replacement Heifers - John B. Hall, Extension Animal Scientist, Beef, Virginia Tech
Replacement heifers need to be of sufficient weight and age to breed successfully. To insure heifers are developed properly from a nutrition and weight aspect, we have used the "Target Weight" concept. The Target Weight is the desired weight of all heifers by the start of the breeding season, and it is expressed as a percentage of mature weight. Recently, considerable discussion occurred on the optimum target weight. Is it 55%, 60% or 65% of mature weight?
Recently, many producers may have read articles discussing the success some western ranchers and researchers had with developing heifers to a lighter target weight to reduce development costs. But is what works in the Sandhills of Nebraska right for Virginia? Let's review some facts.
All cows are not the same. The cows in the Nebraska studies were composite cows of a moderate body size. In addition, the composite was of several breeds known for reaching puberty early and at light weights. Finally, the cattle were well adapted to the limited resources of the Nebraska Sandhills. So the heifers in the Nebraska study tend to reach puberty at a younger age and lower weights than our Virginia cattle.
In contrast, Virginia cow/calf producers have been pushing for increased growth and milk production. While this makes our VA cattle potentially more productive because of our abundant forage resources, it also makes them more "high octane" cattle. Genetically, Virginian cattle will partition nutrients towards growth which may delay puberty. In addition, our cattle are large with the average cow in VA herds weighing between 1250 lbs and 1350 lbs. The combination of larger mature size, and greater growth and milking ability means the typical Virginia heifer will be older and heavier at puberty.
Not all operations are the same. In a recent article, a large ranch reported on significant decreases in cost of heifer development when heifers were developed to only 55% of mature weight. Because of the large size of the operation, small reductions in feed costs add up to big savings. For our smaller VA herds, the savings will not be as great.
Also, this large ranch had the luxury of developing all or almost all of their heifer crop then keeping the ones that became pregnant and retaining ownership on the open heifers. While retaining ownership on open heifers is certainly an option for Virginia producers, most operations in our state will have to work with other producers to put together a truckload of heifers to go to the feedlot or use the VA Retained Ownership Program (VA ROP) to add-value to these heifers. Also, many smaller operations can't gamble on having too many open heifers.
The 65% target is right for Virginia. Due to the type of cattle we produce as well as the current value of replacement heifers, the target of 65% of mature weight should be the goal of producers developing replacement heifers in Virginia. This means a majority of the heifers should be at least 65% of their mature weight by the beginning of the breeding season.
So how can we use target weight in developing heifers? Producers can use this method to estimate the average daily gain (lbs./day) each heifer must achieve from weaning to breeding. First, find the average weight of the mature cows in Table 1. Then subtract the average heifer weaning weight from the target weight. The result is the average pounds each heifer needs to gain from weaning until breeding. If you divide the pounds needed to gain by the number of days until breeding, the result is the average daily gain needed from weaning until breeding.
| Table 1. Target weights for heifers using 65% of mature weight. | |
|
Mature Weight of Cows in Herd (lbs) |
Target Weight for Heifers (lbs) |
|
1150 |
750 |
|
1200 |
780 |
|
1250 |
815 |
|
1300 |
845 |
|
1350 |
875 |
|
1400 |
910 |
Here's an example. The average cow at Mostly Vertical Farm (MVF) is 1300 lbs. The average weaning weight of MVF heifers is 525 lbs. Heifers are weaned on November 1 and the breeding season starts on May 1. That makes the number days from weaning until breeding is 181, so let's call it 180. Here's the math.
So the MVF heifers need to gain about 1.8 lbs per day from weaning until breeding. By working with his Extension Animal Science agent or local nutritionist the MVF manager can design a diet to meet the needs of these heifers using resources that are on the farm or locally available.
Research indicates that reaching the target weight is the most important nutritional factor in heifer development. Whether heifers gain at a steady rate from weaning until breeding or gain most of their weight in late fall or early spring does not appear to have dramatic effects on the percentage of heifers that become pregnant. There may be some limited effects on milk production, but if highly nutritious forage is available for calves between 4 months and weaning there is little impact on weaning weight.
Now is the time that producers with spring calving herds should determine the target weight their heifers need to reach by breeding and the average daily gain to get heifers to that goal.
Impact of Cow Size on Nutrient Needs - Dr. Rick Rasby, Professor of Animal Science, Animal Science, University of Nebraska - Lincoln, Lincoln, NE
Nutrient needs for cows of different body weights are not the same. Cows that weigh 1,300 pounds have a greater nutrient (pounds of protein, pounds of energy (TDN), ounces of mineral, etc) requirement compared to cows that weigh 1,000 pounds. If a 1,000 pound cow and a 1,300 pound cow are grazing the same forage resource, the 1,300 pound cow will need to consume more of that forage to meet her requirements. Maintenance feed intake is proportional to metabolic body weight which is described as body weight to the 3/4 power (body wt.3/4). Metabolic body weight isn't just weight of the animal but also describes the surface area of the animal. Heavier cows eat more feed to meet their requirements. The question is: how much more do heavier cows eat?? Data suggests that for each 10% increase in body weight, there is not a 10% increase in maintenance feed intake. The data suggests about a 7% increase in feed intake for each 10% increase in live weight. A 1,300 pound cow is will consume 22% more feed than the 1,000 pound female although there is a 30% difference in body weight.
Using the Body Condition Score - Rory Lewandowski, Extension Educator, Athens County
One management tool that all beef producers should be using is the body condition scoring (BCS) system. The BCS system allows producers to determine if a cow or particular group of cattle needs to be on a higher, or in some cases lower, nutritional plane in preparation for calving, breeding, or even day-to-day maintenance. Even if forages and feeds have been tested and analyzed, the producer should be monitoring the BCS of cattle to evaluate if cattle are responding as the test results predicted. Monitoring body condition score over time will help a producer evaluate how well his or her management practices match up with the nutritional and health needs of the cattle herd. Using the BCS system can help the beef producer group cattle into different feeding regimes, according to nutritional needs. Some critical times to body condition score cattle are: at weaning, 60 days before calving, calving, beginning of the breeding season and mid-summer.
Weaning is a critical time to body condition score cows because a BCS of 5 to 6 should be achieved before the onset of cold winter weather. Studies have shown that it is difficult to put body condition on a thin cow during cold weather. Remember that a couple of factors work against gaining body condition during the winter period. First, the cold itself raises nutritional requirements, second, many cattlemen do not have the hay or forage quality necessary to meet more than body maintenance requirements during the winter, or if they do, they are saving it for the late gestation period, and finally, as gestation progresses, nutritional requirements increase. The period following weaning is generally the time of lowest nutritional requirements for the cow, so feeding even a lower quality forage can provide enough nutrients for maintenance requirements plus weight gain. Trying to put weight gain on a thin cow during the winter months is not impossible, but it is expensive because it requires a more nutrient dense feedstuff.
For those who might not be familiar with the BCS system, or could use a quick review, here is the description of the numerical ratings.
EMACIATED: Starving and weak. No palpable fat detectable over back, hip bones, or ribs. Tail-head and ribs project quite prominently.
POOR: Poor milk production and reproduction. Chances of rebreeding slim. Cow still emaciated but tail-head and ribs less prominent. Backbone is still rather sharp to the touch but some tissue exists along the backbone.
THIN: Poor milk production and reproduction. Ribs are still individually identifiable but not quite as sharp to the touch. Obvious palpable fat along the spine and over the tail-head with some tissue over top portion of the ribs.
BORDERLINE: Reproduction bordering on inadequate. Individual ribs no longer visually obvious. Individual spines can be identified on palpation but feel rounded, rather than sharp. Some fat cover over ribs and hip bones.
MODERATE: Minimum necessary for efficient rebreeding and good milk production. Cow has generally good overall appearance. Upon palpation, fat cover over ribs feels spongy and the area on either side of the tail-head now has palpable fat cover.
OPTIMUM: Milk production and rebreeding very acceptable. Firm pressure now has to be applied to feel spinous processes. A high degree of fat is palpable over the ribs and around the tail-head.
GOOD: Maximum condition needed for efficient reproduction. Cow appears fleshy and obviously carries considerable fat. Very spongy fat cover over the ribs and around the tail-head. Some fat around vulva and crotch.
FAT: Very fleshy. No advantage in having the cow in this condition. Backbone almost impossible to palpate. Cow has larger fat deposits over ribs, around tail-head, and below vulva.
EXTREMELY FAT: The fat may cause calving problems. Cow extremely wasty and patchy. Tail-head and hips buried in fatty tissue. Bone structure no longer visible and barely palpable. The animal's mobility may be impaired by fat deposits.
The BCS system is a low-cost management tool that can be effective in helping beef producers evaluate their management practices when used on a consistent basis.
EDITOR's NOTE: To read more about strategies for altering BCS in different seasons, review the section on the subject in the Maximizing Fall and Winter Grazing of Beef Cows and Stocker Cattle bulletin found in the OSU Beef Team Library.
Forage Focus: Roundup Ready Grazing Tolerant Alfalfa: Application For Kentucky - Garry D. Lacefield and S. Ray Smith, Extension Forage Specialists, University of Kentucky
All of you have heard of the release of Roundup Ready alfalfa, but did you know that there is a Roundup Ready Grazing Tolerant variety. Dr. Joe Bouton has spent the last 10 years developing an improved Alfagraze with high levels of disease resistance and less fall dormancy. He teamed up with Monsanto to introduce the Roundup Ready gene into this variety and seed will be available for sale next spring for $7 to 8 per pound. We are cooperating with forage researchers from across the southeast in a series of experiments and demonstrations for this variety. We are looking to see how this variety can be best used in Kentucky. For example: Should Alfagraze 300RR be grazed in pure stands? Does it make sense to use this variety to clean up a weedy field for a year and then interseed with orchardgrass, novel endophyte tall fescue, and other forage species? Will Alfagraze 300RR improve the success rate of establishing alfalfa into stands of KY31? We look forward to reporting the results from this research in upcoming issues of Forage News.
Weekly Roberts Agricultural Commodity Market Report - Mike Roberts, Commodity Marketing Agent, Virginia Tech
LIVE CATTLE in Chicago (CME) closed higher on strength from struggling grain markets and short covering on Monday. The DEC'06LC at $85.750/cwt, up $0.050/cwt. The FEB'07LC closed up $0.100/cwt at $88.850/cwt. Last week, U.S. Plains fed cattle traded $3/cwt lower amid a week tone that is expected to dominate throughout this week. Beef demand usually eases up prior to Thanksgiving as pork and turkey demand pick up. USDA data for choice beef cutout on Friday was placed at $143.46/cwt, up $0.15/cwt. Spread unwinding may again offset any continuation of the Goldman Sachs rolling of long positions from December into February. The roll officially ends on Monday. The average beef plant margin for Monday was estimated at a negative $13.95/head, up $9.00/head from last Friday's negative $22.95/head, according to HedgersEdge.com. Cash sellers are encouraged to keep marketings current. This rebound is one of those opportunities to protect a portion of 4th quarter '06 and 1st quarter '07 marketings. Corn users should consider pricing some near-term inputs on this market dip.
FEEDER CATTLE at the CME closed down on Monday with the NOV'06FC futures contract finishing at $97.800/cwt, off $1.000/cwt. This was $2.55/cwt lower than this time last week. The JAN'07FC contract finished at $95.425/cwt, off $0.800/cwt and $0.90/cwt lower than last Monday. The April, May, and August contracts finished higher a range of $0.15/cwt-$0.45/cwt. Feeders traded mixed after a slow start as CBOT corn futures reversed early gains. Higher CBOT corn futures sent feeder cattle futures lower amid rising feed costs and slow demand from feed lot buyers. Expectations that feeders will be cheaper in the coming days kept pressure on the November contract. The CME Feeder Cattle Index for November 9 was placed at $100.92, off $0.52/cwt and the lowest it's been since May 11. Cash sellers are still encouraged to consider protecting a portion of 4th quarter '06 and 1st quarter '07 marketings at this point. Corn users should consider pricing some near-term inputs on this market dip.
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BEEF Cattle is a weekly publication of Ohio State University Extension in Fairfield County and the OSU Beef Team. Contributors include members of the Beef Team and other beef cattle specialists and economists from across the U.S.
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