Bird BW Research Articles

308 Effect of Thermal Variation During Late-Stage Incubation and Sex on Broiler Chicken Body Weight and Carcass Parts Uniformity

Abstract Low uniformity of broiler live body weight, carcass, and parts weights can reduce overall processing yields and profitability. The objective of this study was to evaluate the effects of thermal manipulation (TM) during late-stage incubation (LSI) and sex on the uniformity and coefficient of variation (CV) in high yielding broilers. Yield Plus ′ Ross 708 broiler breeder eggs (n = 2,160) were incubated at 37.5 °C from embryonic day (ED) 0 to 10. From ED 11 to 18, eggs were incubated at 1 of 3 air temperature set points: 37.5 °C (CTL), 36.4 °C (COLD), or 38.6 °C (HOT; n = 2 incubators per treatment). On ED 18, all eggs were transferred to baskets in hatchers set to 36.7 °C. Chicks were vent sexed, placed in floor pens blocked by incubation treatment and sex (n = 6 replicate pens of 30 birds per treatment), and fed a common diet. Broilers were individually weighed at d 9, 23, and 32, then, the 15 birds from each pen closest to the pen median BW were processed on d 33. The distance of each bird BW from the pen mean and median, TM treatment, sex, and whole flock BW over time, uniformity of BW (within 10% of the mean), and intra-pen CV were calculated. Data were analyzed as a 2-way ANOVA using the GLIMMIX procedure of SAS ver. 9.4 with TM treatment and broiler sex serving as the main effects. Means were separated at P ≤ 0.05 with the PDIFF option. On d 9, a TM by sex interaction was observed, and the BW of female CTL chicks was less variable from the pen mean compared with broilers hatched from COLD and females from HOT incubators (P ≤ 0.026). On d 9, sub-optimal incubation temperatures (HOT and COLD) during LSI resulted in higher individual female bird BW variation from the pen mean and median (P = 0.013). Incubating chicks in COLD incubators during LSI increased d-9 individual bird BW distance from the treatment, sex, and flock mean and median BW compared with CTL and HOT (P ≤ 0.037). In addition, BW uniformity within a pen was less in broilers hatched from COLD incubators than both CTL and HOT on d 9 (P = 0.033) and tended to be less on d 32 (P = 0.099). The inverse was observed for CV (P ≤ 0.040). Broilers hatched from COLD and HOT incubators had greater CV for carcass (P = 0.049) and wing (P = 0.028) as well as drumstick (P = 0.079) weights. These results indicate that sub-optimal LSI conditions can negatively influence uniformity of broiler live BW, carcass and parts weights and highlights the importance of achieving optimal incubation conditions.

The impact of marker selection, in-line near-infrared spectroscopy (NIR), and feed mix time on the coefficient of variation (mix uniformity), body weight uniformity and broiler growth performance during the starter, grower, and finisher periods

Most feed manufacturers in the United States use the same mixing time (and thus mix uniformity) throughout the growing period regardless of age and consumption patterns. However, research evaluating the optimum mixing time requirements and novel analysis methods, such as in-line near-infrared (NIR) spectroscopy, on the coefficient of variation (CV) and growth performance of broilers throughout the production phases is sparse. Two experiments were conducted to determine the effects of marker selection, in-line NIR, and varying mix times on mix uniformity, broiler growth performance, and body weight uniformity from 1 to 42 d of age. Feed was manufactured utilizing a 1,815-kg counterpoise ribbon mixer. In both experiments, feed was mixed for 4.5 min (3 min dry mix and 90 s of wet mix) and 30 s (0 s dry mix and 30 s wet mix) to obtain a standard mix (SM) and an abbreviated mix (AM), respectively. Experiment 1 constituted a 2×2×4 factorial arrangement of 2 mix times, (4.5 and 0.5 min), 2 batch sizes (908 and 1,815 kg), and 4 methodologies to evaluate mixer performance (sodium chloride, Microtracers (Red#40 and Blue#40), and in-line NIR). In experiment 2, broilers received different mix time combinations: 1) SM from 1 to 42 d, 2) SM from 1 to 28 d and AM from 28 to 42 d, 3) SM from 1 to 14 d and AM from 14 to 42 d, and 4) AM from 1 to 42 d. In both experiments, selecting a single source marker provided a more accurate estimation of mixer CV in SM and AM diets (P < 0.05). In experiment 2, mix time did not influence BW, feed intake (FI), FCR, or individual bird BW CV from 1 to 42 d of age (P > 0.05). These data indicated that mixer CV differed depending on total mix time and methodology used and diets with a reduced mix time may not necessarily influence growth performance and BW uniformity during the starter, grower, and finisher periods of broilers.

Modeling gait score of broiler chicken via production and behavioral data

Lameness in broilers may be associated with pain and is considered a major broiler production and welfare concern. Manual gait score assessment in commercial broiler houses is discrete, time-consuming, and laborious. As such, automatic methods for broiler gait score assessment are urgently needed. The objective of this study was to identify the relation of broiler gait score with several productions and behavioral metrics (bird BW, age, activity, and distribution), and establish three gait score prediction models for automatic gait score estimations in broiler farms with automatic weighing systems, camera systems, or both. Sixteen pens were used to rear Cobb 500 and Ross 708 broilers for eight and nine weeks, respectively (eight pens/strain, 12 birds/pen). The gait scores of all birds were assessed weekly by trained assessors following a six-point (0–5) scoring protocol from the third week. The pen’s average BW was measured weekly. Top-view cameras were installed to continuously record videos of broilers in all 16 pens. Images were extracted from video clips (10 min/hour) during a 16-hour light period to determine the activity index and distribution index through image processing. The gait score was positively correlated with BW (R2 = 0.97 for Cobb and R2 = 0.96 for Ross), while negatively correlated with activity (R2 = 0.78 for Cobb and R2 = 0.73 for Ross). The three models showed high accuracies in predicting broiler gait score based on variables of BW, age, activity index, and distribution index (R2 = 0.90–0.91, RMSE = 0.38–0.41). The findings of this study demonstrated the potential of estimating broiler gait score using bird BW, age, activity index, and distribution index. This information will assist in the development of automated gait score assessment systems in broiler production.

Effects of live and killed vaccines against Mycoplasma gallisepticum on the performance characteristics of commercial layer chickens

Different vaccine strains of Mycoplasma gallisepticum have been used on multiple-age commercial layer farms in an effort to protect birds against virulent field-strain infections. Use of the F-strain of M. gallisepticum (FMG), as an overlay vaccine during lay, may be necessary because of the lower level of protection afforded by M. gallisepticum vaccines of low virulence given before lay. Two replicate trials were conducted to investigate effects of live and killed M. gallisepticum vaccines administered individually and in combination before lay, in conjunction with an FMG vaccine overlay after peak egg production (EP), on the performance characteristics of commercial layers. The following treatments were utilized at 10 wk of age (woa): 1) control (no vaccinations); 2) ts11 strain M. gallisepticum (ts11MG) vaccine; 3) M. gallisepticum-Bacterin vaccine (MG-Bacterin); and 4) ts11MG and MG-Bacterin vaccines combination. At 45 woa, half of the birds were overlaid with an FMG vaccine. Hen mortality, BW, egg weight, percentage hen-day EP, egg blood spots, and egg meat spots were determined at various time periods between 18 and 52 woa. The data from each trial were pooled. Treatment did not affect performance in interval I (23 to 45 woa). However, during interval II (46 to 52 woa), the EP of control and MG-Bacterin-vaccinated birds that later received an FMG vaccine overlay was lower than that in the other treatment groups. Furthermore, treatment application reduced bird BW during interval II. Despite the effects on BW and EP, no differences were observed for egg blood or meat spots among the various treatments. It is suggested that the vaccination of commercial layers before lay with ts11MG, but not MG-Bacterin, may reduce the negative impacts of an FMG overlay vaccination given during lay. These results establish that the vaccination of pullets with ts11MG in combination with the vaccination of hens with an FMG overlay, for continual protection against field-strain M. gallisepticum infections, may be used without suppressing performance.

Relationships of incubational hatching egg characteristics to posthatch body weight and processing yield in Ross × Ross 708 broilers ,

The characteristics of broiler hatching eggs have the potential to effect broiler posthatch growth and processing yield. The association of set egg weight (SEW), length of incubation (LI), and mean daily percentage of incubational weight loss (MDPEWL) of embryonated Ross × Ross 708 broiler hatching eggs with subsequent posthatch BW and processing yield was investigated. Sixty Ross × Ross 708 broiler hatching eggs were randomly set on each of 8 replicate tray levels of an incubator. Weight loss of individual embryonated eggs between 0 and 10.5, 10.5 and 18.5, and 0 and 18.5 d of incubation was determined for the calculation of MDPEWL. Furthermore, on 18.5 d of incubation, embryonated eggs were transferred to a hatcher unit where they were individually monitored for hatch every 12 h for determination of LI. Chicks were placed in corresponding replicate floor pens and were grown out from 0 (21.5 d of incubation) to 49 d posthatch. Live bird BW as a percentage of SEW on 21.0 d of incubation and d 0 and 49 posthatch, and bird sex on d 49 posthatch were determined. After commercial processing, carcass weight as a percentage of SEW, and carcass, abdominal fat pad, wings, breast muscle, tenders, drumsticks, and thighs weights as percentages of live BW were determined. Bird BW on 21.0 d of incubation and on d 0 and 49 posthatch were positively correlated or interrelated with SEW. Between 0 and 10.5 d of incubation, MDPEWL was negatively correlated with absolute and relative BW on 21.0 d of incubation, absolute BW on d 0 posthatch, and relative tenders weight. Further, LI was positively correlated with absolute and relative BW on 21.0 d of incubation and d 0 posthatch, but was negatively correlated with relative (percentage of live BW) carcass weight on d 49 posthatch. The MDPEWL of modern strain broiler hatching eggs should be closely monitored, particularly during the first half of incubation, for the regulation of LI and hatchling BW and for their potential effects on processing yield characteristics.

Performance and preference of broiler chickens exposed to different lighting sources

SUMMARY Vision is important in poultry behavior and welfare. Poultry have highly specialized visual systems, and the majority of their behavior is mediated by vision. In the present study, we evaluated the lighting preference of broiler chickens exposed to different lighting sources and their production performance. In the first portion of the study, we evaluated the preference of birds for white and yellow lighting provided by light-emitting diode (LED) bulbs. Bird preference was assessed by videos recorded during the experiment. In the second portion of the study, we evaluated the performance of broiler chickens exposed to LED and compact fluorescent lamps (CFL). Performance was assessed in terms of mortality rate, bird BW, daily BW gain, feed consumption, and feed conversion. The chickens occupied environments with yellow and white LED lighting evenly and did not show any behavioral sign of preference for one of the environments. However, birds presented greater feed consumption at 21, 28, and 35 d of age when exposed to white LED lighting. Generally, birds exposed to LED lighting presented better production performance than birds under the CFL. Seven-day-old male chickens presented better feed conversion under LED illumination than did males of the same age under CFL.

Effects of increasing dietary concentrations of corn naturally contaminated with deoxynivalenol on broiler and turkey poult performance and response to lipopolysaccharide

In this study, 2 experiments determined the effects of increasing dietary concentrations of deoxynivalenol (DON) on performance, intestinal morphology, and measures of innate immunity in broilers and turkeys. For experiment 1, the 3-wk study used 5 concentrations of DON (up to 18 or 10 mg of DON/kg of feed in broilers or turkeys, respectively) from naturally contaminated corn. The BW gains were cubically or quadratically affected by the increasing dietary concentrations of DON for broilers and turkeys, respectively; however, feed consumption was not affected. For experiment 2, the birds were subsequently injected or not injected with lipopolysaccharide (LPS) 24 h before tissue and blood sample collection. Dietary DON had no effect on intestinal crypt depth, but linearly increased the mid-ileal villus height in broilers (P = 0.04). An interaction was observed between the LPS challenge and the dietary DON with regards to heterophil to lymphocyte ratio (P < 0.05) in broilers, but not in turkeys. The cecal tonsil cell phagocytosis of microbeads was not affected by the dietary concentration of DON either with or without the subsequent LPS challenge for both broilers and turkeys. Conversely, the phagocytic capacity of cecal tonsil cells to engulf killed Staphylococcus aureus was significantly reduced (over 2.5-fold) when broilers were fed the highest concentration of dietary DON (non-LPS-challenged; P < 0.05). However, diets containing DON showed no effects on broilers when they were challenged with LPS. Antibody-dependent phagocytosis (S. aureus) was not affected in turkeys fed DON. Overall, corn naturally contaminated with up to 18 or 10 mg/kg of DON (broiler or turkey, respectively) reduced bird BW gain at 21 d of age, reduced antibody-dependent phagocytosis of previously killed S. aureus by cecal tonsil cells in non-LPS-challenged broilers, and greatly decreased heterophil to lymphocyte ratios in LPS-challenged broilers.

Strategies to improve performance and reduce preslaughter Salmonella in organic broilers

SUMMARY The proposed health benefits, product freshness, and concern about antibiotic-resistant bacteria have bolstered sales of organic poultry products. However, outdoor requirements for organic poultry could increase exposure to bacteria, including Salmonella. The objective of this study was to assess the effects of prebiotics and probiotics in feed (experiment 1) and acidifying water treatments (experiment 2) on organic broiler performance and the presence of preslaughter Salmonella. In experiment 1, a prebiotic (MOS), 2 probiotics, and a control treatment were implemented. In experiment 2, raw apple cider vinegar, an organic acid blend, H2 O2, and a control treatment were incorporated into the watering systems. For both experiments, 300 one-day-old Cobb 500 male chicks were randomly assigned to treatment and pen. On d 21, birds were weighed and allocated at 13 per pen within each of the 5 housing locations providing pasture access at the West Virginia University Certified Organic Farm. Data collection occurred from d 21 to 49. On d 21, probiotic 1, the prebiotic, and the organic acid blend yielded the highest BW but demonstrated the same ending bird BW. However, birds provided probiotic 1 and the prebiotic were at least 86 and 72% less likely to be contaminated with Salmonella preslaughter. The lowest bird BW were achieved by birds provided H2 O2 throughout the study; however, these birds were at least 7% less likely to harbor Salmonella preslaughter compared with birds in the control treatment.

The effect of copper in excess of the requirement during the starter period on subsequent performance of broiler chicks

Several researchers have explored the potential of Cu as a growth-promoting agent in the diets of broiler chicks in excess of the current recommended nutritional level (up to 300 mg/kg of the diet). However, it is not clear whether the reported beneficial or toxic effects of extra Cu last until market age if Cu is supplemented to the diet only during the starter period. Therefore, an experiment was conducted using 1-d-old male broiler chicks to investigate the effects of different levels of Cu [0, 125, and 250 ppm of Cu from cupric sulfate pentahydrate (CuSO 4 ·5H 2 O)] in excess of the requirement during the starter period (1 to 21 d) on broiler chick performance, bone development, and gastrointestinal development. The addition of 250 ppm of Cu had significant ( P < 0.05) negative effects on bird BW, BW gain, and feed intake during the earlier parts of the starter period. However, the addition of 125 ppm of Cu improved ( P = 0.05) FCR from 1 to 42 d. Tibia bone ash content and gastrointestinal organ relative weights were not significantly affected ( P > 0.05) by additional Cu supplementation; however, the addition of 250 ppm of Cu to the basal diet significantly ( P < 0.05) increased liver Cu and decreased blood hematocrit (%) at 20 d. Although feeding 250 ppm of Cu during the starter period had negative consequences on bird performance, moderate levels of Cu (125 ppm) had beneficial effects on FCR without having deleterious effects on bird performance at market age. Caution is advised when considering higher levels of Cu (250 ppm) as a feed supplement in broiler diets.

Effects of in ovo injection ofl-carnitine on subsequent broiler chick tissue nutrient profiles

Effects of in ovo injection of L-carnitine on BW and the moisture and nutrient biochemical concentrations of various organs and muscles of Ross x Ross 308 broiler chicks, hatched from eggs laid by a 28-wk-old breeder flock, were determined through 48 d posthatch. Eggs containing live embryos were injected in the amnion with L-carnitine (0.5, 2.0, or 8.0 mg dissolved in 100 microL of a commercial diluent) on d 18 of incubation using an automated egg injector. Three control groups (noninjected and injected with or without diluent) were also included. On d 0, 3, 10, 28, and 48 posthatch, bird BW and the proportional weights and moisture concentrations of various organs and muscles were determined. Glycogen, glucose, protein, and fat concentrations were also determined in certain tissue samples. Bird BW; proportional liver weight; breast, thigh, and gastrocnemius muscle moisture; liver glycogen, glucose, and protein concentrations; and breast and thigh muscle fat and protein concentrations changed with posthatch bird age. Liver glucose on d 0 and pipping muscle moisture on d 3 posthatch were significantly affected by treatment. In comparison to eggs injected with commercial diluent with no added L-carnitine, liver glucose was reduced by the injection of diluent containing either 0.5 or 8.0 mg of L-carnitine, and pipping muscle moisture was increased by the injection of commercial diluent containing either 0.5 or 2.0 mg of L-carnitine. The modified concentrations of the 2 parameters in response to these treatments were not different from those in noninjected control eggs. In conclusion, L-carnitine added to commercial vaccine diluent at levels between 0.5 and 8.0 mg/100 microL for the commercial injection of broiler hatching eggs may decrease liver glucose and increase pipping muscle moisture concentrations of chicks on d 0 and 3 posthatch, respectively, so that their levels are commensurate with noninjected controls.

Infrared beak treatment method compared with conventional hot-blade trimming in laying hens

Infrared lasers have been widely used for noninvasive surgical applications in human medicine, and their results are reliable, predictable, and reproducible. Infrared lasers have recently been designed for the express purpose of providing a less painful, more precise beak-trimming method compared with conventional beak trimming. This study was designed to examine the potential of the infrared (IR) beak treatment to provide a welfare-friendly alternative to the conventional hot-blade method for chickens. The birds were beak trimmed by IR at the hatchery or by hot blade at 7 to 10 d of age in a commercial production setting, in accordance with standard procedures. The beak morphology and associated physiological characteristics, including production and aggressive behavior of the birds, were analyzed at 30 wk of age. There was no difference in egg production or bird BW between the 2 beak-trimming treatments. Birds also exhibited no difference in stress physiology measured in the study, such as fluctuating asymmetry and heterophil and lymphocyte profiles. However, birds receiving the IR treatment showed a superior feather condition and reduced aggressiveness under high light intensity, even though they had longer beak stumps. The results may indicate that the IR beak treatment may reduce the damage done by aggressive pecking and feather pecking. Indeed, IR trimming may provide a more welfare-friendly alternative to conventional beak trimming without compromising productivity.

Effect of Dietary Mannan Oligosaccharide from Bio-Mos or SAF-Mannan on Live Performance of Broiler Chickens

A 42-d broiler pen trial was conducted to evaluate the effects of dietary mannan oligosaccharide (MOS) from either of 2 commercial products, Bio-Mos (Alltech Inc., Nicholasville, KY) or SAF-Mannan (S. I. LeSaffre, Cedex, France) each at 2 levels of inclusion on live performance. The MOS, derived from the outer portion of yeast cell walls, is reported to have several beneficial modes of action including 1) pathogen adsorption (agglutination); 2) improved intestinal integrity (e.g., villi height); and 3) immune modulation. Diets were fed in 3 phases, and treatments included a control, 2 Bio-Mos treatments (1.0 kg/ton in starter and 0 or 0.5 kg/ton in grower and finisher feeds), and 2 SAF-Mannan treatments (0.5 kg/ton in starter and 0 or 0.5 kg/ton in grower and finisher feeds), according to the manufacturers’ recommendations. Birds fed Bio-Mos at 1.0/0.5/0.5 (starter/grower/finisher) kg/ton diets had significantly greater BW at 42 d than birds fed control or SAF-Mannan-supplemented diets, whereas results for the Bio-Mos 1.0/0/0 kg/ton diets were intermediate. Supplementation of diets with Bio-Mos at 1.0/0.5/0.5 kg/ton may improve broiler BW at market ages compared with the unsupplemented diets. Feed consumption was lower from 0 to 21 d in the SAF-Mannan treatments compared with other treatments. No significant differences were found for feed conversion or mortality for any of the treatments. Overall, Bio-Mos had a greater effect on bird BW compared with the other variables measured.

Effects of Supplemental Dietary Phytase and 25-Hydroxycholecalciferol on the Blood Characteristics of Commercial Layers Inoculated Before or at the Onset of Lay with the F-Strain of Mycoplasma gallisepticum

In 3 trials, the effects of dietary supplementation with phytase (PHY) and 25-hydroxycholecalciferol on BW and the blood characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed at 34, 50, and 58 wk of age. Experimental layer diets, which included either a basal control diet or the same diet supplemented with 0.025% PHY and 25-hydroxycholecalciferol, were fed from 20 through 58 wk of age. The supplemented diet decreased blood hematocrit values across bird age, inoculation type (sham vs. F-strain M. gallisepticum), and age of inoculation (prelay vs. onset of lay). Phytase- and 25-hydroxycholecalciferol-supplemented diets reduced bird BW in sham-inoculated control birds across bird age and age of inoculation. This effect was not observed in F-strain M. gallisepticum-inoculated birds. Furthermore, across diet (control vs. supplemented) and inoculation type, total plasma protein concentration at 34 wk of age was higher in birds that were inoculated at the onset of lay compared with those inoculated prelay. Diet, inoculation type, and inoculation age had no effect on mortality, reproductive organ histopathological lesion scores, or serum cholesterol and Ca concentrations. In conclusion, throughout lay, the supplementation of commercial layer diets with PHY may lower hematocrit, and inoculation with F-strain M. gallisepticum prelay or at the onset of lay may ameliorate the depressing effects of dietary PHY and 25-hydroxycholecalciferol supplementation on hen BW.

Use of a litter material made from cotton waste, gypsum, and old newsprint for rearing broiler chickens

Three experiments, which included 4 broiler flocks, were conducted to examine the usefulness of a novel bedding material for rearing broilers. The control bedding was pine shavings. The novel bedding, aGroChips (AC), was a chopped material made from cotton lint waste, gypsum, and old newsprint using a proprietary paper manufacturing process (Novovita, Inc., Raleigh, NC). All birds were fed the same feeding program: starter from 0 to 3 wk, grower from 3 to 5 or 6 wk, and finisher during the last week. Birds were marketed at either 6 or 7 wk of age. Feed consumption by pen and individual bird BW were measured at 3 and 6 or 7 wk. Mean BW and feed conversion, adjusted to include weight of mortality, were calculated. A sample of birds (n = 10) from each pen was evaluated for hock and foot pad condition. Each pen was evaluated at the end of the trial for litter cake index in 3 of the 4 flocks. Litter cake index scores were generally higher for birds reared on AC litters. There were no other differences in bird performance for any of the flocks. In conclusion, broilers reared on AC bedding perform as well as those reared on pine shavings.

Effect of dietary phosphorus and phytase levels on the reproductive performance of large white turkey breeder hens

An experiment was conducted to determine the effect of dietary P levels and dietary phytase enzyme (E) inclusion on Large White turkey breeder hen reproductive performance from 31 to 62 wk of age. Hens were placed in a curtain-sided house with 48 pens (10 birds per pen; 8 pens per treatment) at 31 wk and were fed a breeder ration with treatments as follows: HP, dietary available P = 0.55%; HPE, HP + E; MP, dietary available P = 0.35%; MPE, MP + E; LP, dietary available P = 0.17%; and LPE, LP + E. Feed and water were available ad libitum for 28 wk of lay. Diets were fed in mash form, and all other nutrients were formulated to meet or exceed NRC requirements. All hens were photostimulated in January (31 wk) with 15.5 h of light daily. Production data were recorded on a pen basis. Individual bird BW and feed consumption, by pen, were determined at monthly intervals from 31 to 62 wk. Hens were observed for weekly reproductive performance for hen housed egg production, hen-day egg production, settable eggs, cumulative settable eggs, hens out of lay, and hen mortality and for biweekly performance for egg fertility, hatchability of all eggs, hatchability of fertile eggs, egg weight loss, conductance, conductance constant (k), and embryonic mortality. Egg weight, eggshell thickness, egg components, and albumen and yolk P were measured monthly. At 62 wk of age, hen tibia P, plasma P, total fecal P, and water-soluble fecal P were determined. Decreasing dietary P resulted in no decreases in reproductive performance for turkey breeder hens to 62 wk. Additionally, decreased dietary P resulted in decreased total fecal P and water-soluble fecal P. Feeding turkey breeder hens dietary phytase enzyme resulted in significantly fewer hens going out of lay; however, this was not reflected in hen housed egg production. It was concluded that phosphorus could be lowered in turkey breeder hen diets, compared with current surveyed industry levels, without impairing reproductive performance.

Relationship of Sex, Age, and Body Weight to Broiler Carcass Yield and Offal Production

Male and female broilers (feather-sexable strain) at 28, 35, 42, and 49 days of age were utilized to determine the effect of sex, age, and BW on yield of various offal and edible carcass components. Individual bird BW ranged from 756 to 2,970 g. During processing, weight of blood, feathers, head, neck, feet, preen gland, heart, liver, gizzard, gastrointestinal tract, fat pad, hind half (legs, thighs, and saddle), wings, Pectoralis major, breast skin, Pectoralis minor, back with lungs, rib cage, water uptake, and whole dressed carcass were determined. Regression analyses were used to generate equations describing the relationship between carcass components and BW for each sex and with the sexes combined. The data were also subjected to analysis of variance to determine age and sex effects on an absolute weight and percentage of live BW basis.Yields of body components changed with increasing age and BW. In general, the percentage of edible components increased, and the percentage of offal decreased with increasing age and BW. When expressed on a percentage of live BW basis, significant sex effects existed for feathers, head, neck, feet, heart, liver, fat pad, hind half, breast skin, and Pectoralis minor. Thus, the yield of offal components vary more by sex than does yield of edible carcass components.