R. M. Hulet
Department of Poultry Science
Pennsylvania State University
U.S.A.
Introduction
Many factors influence meat yield of commercial turkeys. Among them, the chief factors are Nutrition, Management, Market Weight and Genetics. In our modern turkey industry, there is increasing pressure to produce the most economical product that is possible. Because of bird variation, standardizing management and nutrition to allow the genetic potential to be expressed is a major goal of commercial farms. Information on growth, feed conversion, and mortality can help determine the efficiency of production of birds at different ages. However, marketing (sales of particular product lines) determines what size of bird must be sold to meet consumer demands and product specifications.
Marketing of tom turkeys is focused on three live weight product lines. The largest marketing size for turkeys is the 38 to 44 lb tom that is most efficient on a processing costs per pound basis (lbs/hr) but not necessarily most efficient for live¬production costs ($/lb). The most common other size of tom produced is the 28 to 30 lb tom. Hens are still mainly produced for whole bird production (14 to 16 lb live weight), while the second most popular size of turkey hen produced is the heavy hen (20 to 22 lb). Therefore, depending on the market focus or niche, decisions for selection of genetics, nutrition, and management can change.
Yield can be affected by many factors such as feeding programs, selective breeding, and advancements in management practices. Dietary programs to increase breast meat yield have concentrated on increasing dietary lysine, methionine, and threonine (Noll et. al., 2003; Waibel, et. al., 2000; Waldroup, et. al, 1998). They have shown that breast meat is responsive to levels of amino acids and protein above that required for growth. However, if yield of breast meat is not the critical element for profitability of the company, then added protein and amino acids are just increases in meat cost. For some markets, turkey breast meat is the most economically important portion of the turkey carcass and therefore would be the most important factor for successful production and profitability.
Different management strategies such as pelleting versus mash feed form, number of feeds, bird density, temperature, ventilation rate, drinker type, and lighting duration and intensity can influence growth of turkeys (Crouch et. al., 2000; Strangeland et.al., 1999; Waldroup et. al., 1997). Management strategies have not necessarily been shown to influence breast meat yield, but by affecting uniformity by decreasing variability, improved meat production is obtained.
By standardizing the management, determining the body weight goal, and utilizing dietary form, program, and number of feeds, birds can be evaluated for a particular company and determine what the genetic potential for turkeys under an ideal growing environment. Trials were conducted not so much as a recommendation for a particular strain, but as a method that could be followed to determine under a companies standard dietary, management, and body weight specification, what bird will perform the best for them. It is also understood that genetic progress is dynamic and what we see at one point in time, changes as the next genetic generation of turkey strain is hatched or new strain developed for commercial consumption.
Materials and Methods
Several trials were conducted to evaluate genetic stocks of current commercial turkey strains, BUTA, Hybrid, and Nicholas. The objective of three trials were to determine the growth performance and meat yield of commercial and heavy hens, as well as for large toms grown to either 38 or 44 lbs.
In our first trial, 960 hen turkeys (320 birds from BUTA, Hybrid, and Nicholas) were placed into six brooder pens for three weeks at a density of 0.55 ft2/bird. After three weeks all birds were randomized into twenty-four pens by strain with 40 birds per pen (2.2 ft2/bird). Birds had access to Ziggety 3.5 " nipple drinkers for the first six weeks and on Plasson bell drinkers from 6 weeks to marketing. All birds were given feed and water ad libitum. Birds were given a commercial diet with feed changes at 0, 21, 42, and 84 days of age. Birds were weighed and feed intake determined at each feed change and at 105 days of age. At 84 and 105 days of age, 24 hens were sampled from each strain to determine carcass and meat yield of these strains of birds. Growth efficiency was also determined and compared by strain.
In the second trial, 720 tom turkeys of four different strains (BUTA 6, BUTA T2, Hybrid, and Nicholas) were randomized into 8 pens at a density of .98 ft2/bird for three weeks. Birds were again weighted and randomized into 24 pens with six replicate pens per strain treatment at a density of 3.6 ft2/bird. All birds were given free access to feed and water with feed changes at 0, 21, 42, and 84 days of age. Body weight and feed intake were recorded at feed changes and at 120 days of age. Thirty-five birds from each strain were tagged and sent to the processing plant where carcass and meat parts yield were determined. Birds that were trimmed or downgraded (loss of flesh or bone) were not considered in the data presented.
In the last trial, 960 tom turkeys of three different strains (BUTA 6, BUTA T2, and Nicholas) were randomized into 6 pens at a density of .55 ft2/bird for 21 days. Besides strain, calcium and phosphorus treatments (decreased Ca and total P) were included from 77 to 133 days of age. Since the dietary treatment had no effect on tom growth or performance, this information will not be presented. Birds were again weighed and randomized into 24 pens with four replicate pens per strain and Ca/P dietary treatment combinations at a density of 2.9 ft2/bird. All birds were given free access to feed and water with feed changes at 0, 21, 42, 63, 77, and 98 days of age. Body weight and feed intake data were recorded at feed changes and at 133 days of age. Twenty five to twenty¬ eight birds from each strain were processed and carcass and parts yield were determined.
Results
Trial one shows the growth differences that are obtained for hen turkeys raised for either the commercial hen market or for the heavy hen market (Table 1, and 2). Birds grown for the whole bird market would have been processed at 84 days. At this point carcass yield is much more important than is percent meat yield. If one were marketing a whole bird and growing for a whole bird market, the choice would probably favor Strain C who had significantly greater body weight at 84 days than Strain B, with significantly less feed conversion at 105 days than Strain A, and B, and significantly greater carcass yield at 84 days than Strain A or B (Table 3 and 4).
However when these same strains, and essentially the same birds, were grown to 105 days, they had different strain results. The goal of the bird grown to 105 days is more concerned with percent meat yield much than carcass yield. While the decision to market strain C would have been appropriate for 84 days, it could be argued that strain B would be better choice for the 105 day product. Strain B, despite being still significantly smaller, had greater carcass yield and the highest numerical bone-in-breast meat yield. It could be argued that at a similar weight that it would have significantly greater breast meat yield per live weight of turkey produced.
The same amount of breast meat was produced on a much smaller frame – which should be more efficient economically.
Trial two shows the performance of tom turkeys reared to 17 weeks of production or 38 lbs (Table 5, 6, 7, and 8). The body weight growth shows the different growth rates of different strains of turkey. It also shows the difference in genetic traits of the cur rent breeders.
Strain A had significantly greater body weight at 17 wks, and greatest lbs of total breast meat, but breast meat yield was greatest for the Strain C, a strain with significantly less body weight. If the object or trait of greatest economic importance was the rapid production of meat instead of greatest yield, different choices of genetic stock should be made. The attainment of 38.5 lbs in 17 weeks with an untrimmed breast meat yield of 6.5 lbs shows the genetic potential of our modern turkey tom. Other factors must be considered such as mortality when raising toms to heavier weights. However, plant efficiency is calculated on lbs of meat/employee/hour. The larger birds could be harvested earlier from the field; greater tonnage produced yearly by the processing plant and, therefore, increased efficiency through a production year for a company for selecting the right strain.
Trial three was conducted to determine the meat yields obtained by fast growing toms when raised to 19 weeks (133 days). Trial three was conducted to also evaluate the effectiveness of raising birds to heavy weights while decreasing the total amount of Ca and P in the diet. It had been found that turkeys had concentrations of Ca and P in the litter that were 3 to 4 times greater than in layer and broiler litter. It was thought that the greater concern for leg strength lead many nutritionist to over formulate for total Ca and P in the diet; hence, greater deposition in the turkey litter. Some information has been included in Table 13 on mean bone density comparison by strain over both diets. No significant difference in leg problems or bone density was detected when total Ca and P levels were decreased 20 % in the last two feeds (11 to 19 wks).
Growth rates of heavy toms were shown to vary by genetic strain as shown by the body weights at 3, 6, 9, 11, 14, and 19 wks of age (Tables 9, 10). At 19 weeks of age, a difference of nearly 3 lbs was shown between strain C and A and one pound of breast meat difference was found at the same age (Table 11, 12). No significant difference in breast meat yield shown between strains because of the live weight/breast meat variation found within a strain. However, the mean value for breast meat yield for Strain C (20.4 %) was .9% greater than Strain A might approach economic significance since breast meat is the most important part of the carcass.
A means of equalizing and evaluating economic significance has been shown in Table 14. The table ignores many of the costs of production other than feed cost and compares the birds based on cost of the feed and feed consumption as a function of lbs/kg of live weight, carcass, or breast meat. This table again addresses the varying importance of different production parameters involved in the profitability of a company.
Conclusions
Many aspects of production can influence meat yield of commercial turkeys. Differences can be found due to nutrition, management, market weight, and genetic potential. Information was presented to show that our current commercial turkeys have different growth rates and production efficiencies in the production of turkey meat.
Evaluation of genetic strains under common management, common nutrition, and at the desired marketing weight should be done in order to make a decision. Picking the right strain should address efficiency of meat production and goals of performance – meat production versus efficiency of meat production (meat yield) to enable the correct decision to be made.
Current commercial strains vary in growth rate and yield. They have been selected to meet the changing demands of our consuming clients and economics of today. Selection of the proper strain should be made on the basis of data collected while standardizing as many of the other factors and allow the comparison of the genetic potential of the commercial turkey strains.
References
Crouch, A. N., S. P. Lerner, and D. Karunakaran, 2000. Influences of feed quality in the brooding period of commercial turkeys and its subsequent effect on market performance. Poultry Sci. 79(Suppl. 1):67-68.
Noll, S. L., 2002. Feeding for live performance and breast meat yield. In "Proceedings of Multi-State Poultry Meeting", May 14-16, Indianapolis, IN.
Strangeland, V., S.L. Noll, G. Speers, and J. Brannon, 1999. Limiting amino acids and energy utilization in market turkey diets. In "Proceedings 60th Minnesota Nutrition Conference", University of Minnesota, St. Paul, MN.
Waibel, P. E., C. W. Carlson, J. A. Brannon, and S. L. Noll, 2000. Limiting amino acids after methionine and lysine with growing turkeys fed low protein diets. Poultry Sci. 79:1290-1298.
Waldroup, P. W., A. L. Waldroup, and N. B. Anthony, 1997. Response of two strains of Large White male turkeys to amino aid levels when diets are changed at three or four –week intervals. Poultry Sci. 76:1543-1555.
Waldroup, P. W., J. A. England, Kidd, M. T., and B. J. Kerr, 1998. Dietary arginine and lysine in Large white toms. 1. Increasing arginine:lysine ratios does not improve performance when lysine levels are adequate. Poutlry Sci. 77:1364-1370.
