Growth, feed conversions, and yields of turkey parts of three strains of hen turkeys as influenced by age

Body composition and development measured repeatedly by computer tomography during growth in two types of turkeys

Distribution and development of fat, muscles, and bone were studied repeatedly by computer tomography from 4 to 17 wk of age in two commercial strains of turkeys (BUT-9 and Nicholas) of both sexes. Generally, the proportion of total fat and meat increased and bone decreased significantly throughout the experimental period for both strains and sexes. When compared at the same age or body weight, BUT-9 tended to have a higher percentage of meat than did Nicholas (0 to 3 percentage units). From 8 to 17 wk of age, Nicholas showed higher fat percentage and lower bone percentage than BUT-9. Based on this study, regardless of weight at slaughtering, BUT-9 should be preferred. Because males had a significantly higher body weight gain and higher percentage of meat from 8 wk of age, males should be used in production to fit the market for high slaughter weights with large pieces of meat. Because females had a higher meat percentage at young ages compared with males, but showed an earlier fattening and lower weight gain, females should preferably be slaughtered at lower live weights. Computer tomography can be considered an appropriate but expensive method to study body composition and development in turkeys.

Response of two strains of large white male turkeys to amino acid levels when diets are changed at three- or four-week intervals

A study was conducted to evaluate the amino acid recommendations of the NRC (1994) when diets were changed at 3- or 4-wk intervals. Diets formulated to provide from 90 to 115% of recommended amino acid levels were fed to Nicholas (NIC) and British United Turkey (BUT) Large White males from day-old to 24 wk of age; samples of turkeys were processed at 18 and 24 wk. Results indicated that the amino acid levels suggested by NRC are adequate to support maximum body weight gain, feed conversion, and dressing percentage of Large White males grown to 18 or 24 wk when fed on 4-wk intervals. An approximately 5% higher level of amino acids was required to maximize breast yield. When feeds were changed at 3-wk intervals, higher levels of amino acids were required to maximize performance; however, there did not seem to be any difference in the response of the two strains of turkeys to different levels of amino acids in this study.

Comparative growth and development of Nicholas and hybrid toms from 16 to 82 days and effects of protein restriction from 0 to 59 days on growth of hybrid toms through 125 days of age

The objective of this experiment was to study age and diet effects on serial growth of economically important carcass parts of Nicholas (NIC) and Hybrid (HYB) toms. At approximately 14-d intervals from 16 to 82 d, BW and the weight of selected carcass parts were compared in toms from both commercial strains. There were no overall strain differences in BW, although NIC toms were heavier from 31 to 72 d, which resulted in a significant strain by age interaction (P < or = 0.021). The absolute weight of the Pectoralis major (PMAJ; P < or = 0.022) and tibia plus associated muscles (Drum; P < or = 0.051) were increased in NIC toms. The relative weight of the PMAJ (P < or = 0.004) and abdominal fat (72 and 82 d; P < or = 0.023) also were heavier in NIC toms. The relative weight of the drum and Gastrocnemius muscle (GAS-TROC) was heavier in HYB toms, however (P < or = 0.001). A separate set of HYB poults was fed a diet deficient in protein or lysine (PD) from 0 to 8 wk and their growth and carcass development were compared with those fed a Control diet (NRC, 1984). Comparisons also were made at approximately 14-d intervals from 16 to 125 d. The PD diet from 0 to 8 wk significantly reduced BW and absolute breast muscle and leg portion weights. The relative weight of the PMAJ and Pectoralis minor (PMIN) were also reduced in toms fed the PD diets but the thigh and drum (125 d) were increased.

Characterization of carcass development from 14 to 145 days of age in turkey hens from two strains

Body weight and carcass components were measured from 14 to 145 d in Nicholas (NIC) and Hybrid (HYB) strain turkey hens. At most ages, BW of HYB hens was greater than that of NIC and there were small but significant differences in the weight of the Pectoralis minor (PMIN). The relative weight of the PMIN increased in HYB hens from 98 to 145 d. No strain differences in either the absolute or relative weights of the Pectoralis major (PMAJ) were observed. The absolute and relative weights of the tibia plus associated muscles (DRUM) and femur plus associated muscles (THIGH) were significantly heavier in HYB hens. The same was true for the Gastrocnemius muscle (GASTROC). The relative weight of the abdominal fat pad (ABFAT) was significantly increased in NIC hens compared with HYB hens from 70 to 145 d. There was a linear relationship between the relative weight of the PMAJ and BW in hens from both strains (NIC, r2 = .69; HYB, r2 = .51). The relationship between the relative weight of the PMIN and BW was best described with a quadratic model but the r2 in both strains was considerably lower than that for the PMAJ (NIC, r2 = .26; HYB, r2 = .36). The linear relationship between BW and the relative weights of the THIGH and DRUM was negative and positive for ABFAT.

Relationship of sex, strain, and body weight to carcass yield and offal production in turkeys

Three strains of male and female market turkeys (British United Turkeys, Hybrid, and Nicholas) were grown under commercial contract production conditions and slaughtered at a range of BW (4,200 to 17,640 g) and age (13 to 22 wk) that covers the range of commercial market weights in use at the time of the study. During processing, the weight of blood, feathers, head, neck, feet plus shanks, heart, liver, gizzard, lungs, gastrointestinal tract, water uptake, hot and chilled carcass with fat pad, fat pad alone, tail, wings, drumsticks, thigh meat, Pectoralis major, Pectoralis minor, scapula meat, lower back, upper back with ribs, breast skin, thigh skin, thigh bone, and hind half (legs, thighs, and saddle) were determined. The data were subjected to least squares analyses using models that included strain and sex effects relative to live BW. Significant differences in yield between the sexes but not among strains were found for feet plus shanks, gizzard, hot and chilled carcass with fat pad, and scapula meat. Similarly, significant differences in yield among strains but not between sexes alone were found for blood, feathers, heart, and hind half. The relationships of live BW with all other variables showed both strain and sex differences in yield. Whereas whole carcass yield as a function of BW was affected by sex alone, most other components varied by both sex and strain. Thus, choice of strain, sex, and age at slaughter affect the projected production of edible carcass and offal components.

Interaction between step-up versus step-down lighting from four to sixteen weeks on growth and development in turkey hens from two commercial strains

British United Turkeys (BUT) and Nicholas (NIC) hens were exposed to a step-up (10 to 16 h/day) or a step-down (16 to 10 h/day) light program from 4 to 16 wk of age. Lights were increased or decreased by .5h/wk. From 1 to 20 wk, weekly BW data were used to calculate growth curve parameters according to the Gompertz equation. Compared with BUT hens, the slope of the growth curve was greater, but the BW and age at the point of inflection (POI) was decreased in NIC hens. The step-down light program significantly increased the slope of the growth curve, but decreased the BW and age at POI compared with the step-up program. A sample of hens from each strain and program was processed at 16 wk. The relative weight of the Pectoralis minor (P. minor) was increased in BUT hens compared with NIC hens. The absolute and relative weights of the Pectoralis major and the absolute weight of the P. minor were increased in hens from the step-down program compared with the step-up program. The step-up program significantly increased the relative weight of the abdominal fat pad compared with the step-down program, and NIC hens had more abdominal fat than BUT hens. Total carcass lipid was significantly increased by the step-up program, compared with the step-down program, and NIC hens had significantly more carcass lipid than BUT hens.

Genetic association of selection for increased leg muscle and increased shank diameter with body composition and walking ability

Body compositions of a randombred control population (RBC2), a line selected for increased 16-wk BW (F), a line selected for increased shank diameter (FL), and a line selected for increased leg muscle mass (FM) were compared at 16 wk of age. The F line originated from the RBC2 population and the FL and FM lines were developed as sublines of the F line. The F and FL lines were developed through mass selection of BW and shank width, respectively. The FM line was developed through family selection for leg muscle mass. Selection for BW in the F line has resulted in an increase in the proportion of breast muscle and a decrease in the relative amount of leg bone in comparison with the RBC2 population. Selection for increased shank width in the FL line has increased not only shank weight but has produced concomitant increases in the weight of the tibiotarsal and femur bones. Although FL line has also shown a correlated increase in BW in association with increases in shank width the increase in leg bone weight was relatively greater than the increase in BW. Therefore, the relative weights of leg bones in the FL line increased such that they were more similar to the RBC2 population than to the F line. Although the amount of leg muscle increased slightly in the FM line, the relative proportion of leg muscle did not increase significantly. The selection program used was probably ineffective in increasing the proportion of leg muscle because of the high percentage (low selection intensity) of families selected and small family size for estimating family means.(ABSTRACT TRUNCATED AT 250 WORDS)

Research note: Influence of body weight selection on the growth curve of turkeys

The growth curve of a population of turkeys selected for increased 16 wk BW (Line F) and a randombred control population (RBC2) was determined. It was concluded that the Gompertz equation best described the growth pattern of Lines F and RBC2 regardless of sex. Line F had higher BW at hatching, BW and slope at point of inflection (POI), and asymptotic BW than Line RBC2. Age at POI and asymptote were achieved later for Line RBC2 than for Line F. Male turkeys had higher BW and age at POI and BW and age at asymptote than females. Slope at POI was greater for females than for males.

Effects of dietary protein and added fat on turkeys varying in strain, sex, and age. 2. Carcass characteristics

The effects of dietary protein and added fat on carcass characteristics were determined at various ages for female and male turkeys and from three strains: Nicholas Large White (N), Jaindl Large White (JL), and Jaindl Medium White (JM). A total of 1,350 turkeys was divided into 36 pens and fed diets containing 0, 5, or 10% added fat and standard or high protein levels from 8 wk of age to time of processing. One-fourth of the females and one-third of the males from each pen were processed at 16, 20, 24, or 28 wk and at 20, 24, or 28 wk, respectively. Breast meat weight, expressed as a percentage of carcass weight, was greater for JM and JL turkeys than for N turkeys (34.6, 33.9, and 31.7%, respectively), increased with age (31.9, 34.1, and 34.2% at 20, 24, and 28 wk of age, respectively), was greater for females than for males (34.2 and 32.6%, respectively), decreased with added fat (33.7, 33.4, and 33.1% for 0, 5, and 10% fat, respectively) and increased with a 3% addition of dietary protein (33.2 and 33.6%, respectively).

Early protein undernutrition and subsequent realimentation in turkeys. 2. Effect on weights and proportions of organs and tissues

Male and female Large White Nicholas turkeys were fed corn and soybean meal diets for 24 and 20 wk, respectively. The same series was fed with a low protein modification (75% of control in protein and 66% of control in methionine and lysine per Mcal ME) during 0 to 6 wk of age. For the study of organ and tissue growth, six male turkeys per treatment were sampled at 2, 4, 6, 8, 12, 16, 20, and 24 wk of age. Six females per treatment were also sampled at 2, 4, 6, 8, 11, 14, 17, and 20 wk of age. Weights of eviscerated carcass, breast, thigh, drumstick, wing, back, neck, feathers, liver, heart, pancreas, alimentary tract less gizzard, and gizzard were depressed by early protein undernutrition to 6 wk of age. Compared with values for controls, undernutrition increased proportions of the liver, alimentary tract less gizzard, gizzard, and heart at 6 wk of age; proportions of the back, neck, feathers, and pancreas were not affected, but breast and thigh proportions were reduced. Compensatory growth during realimentation eliminated all differences between undernourished and control turkeys in weight and proportions of organs and tissues by 20 wk of age.