Flock Uniformity Research Articles

Effects of Dietary Spray-Dried Bovine Plasma Protein on Broiler Growth Performance and Breast-Meat Yield

Dietary spray-dried plasma protein (SDPP) is effective in improving growth performance of pigs raised in unsanitary conditions. However, little is known about the efficacy of SDPP in improving growth performance and carcass characteristics of broiler chickens. In the present study, graded levels of bovine SDPP (0 to 2% of the diet) were fed to male broiler chickens (Ross 308) from 1 to 42 d of age. The study was divided into 2 experiments, each with 480 chickens, with identical experimental designs. Broilers in the second experiment were raised on the soiled litter from the first experiment, thereby creating 2 environments with different levels of sanitation. Broilers fed the control diet in experiment 2 had higher mortality, lower rate of body weight gain, and were less uniform than broilers fed the control diet in experiment 1, suggesting that reusing the soiled litter in experiment 2 resulted in a relatively more unsanitary environment. Dietary bovine SDPP did not affect growth performance or carcass characteristics in the first experiment, but improved growth rate, feed conversion, breast-meat yield (as a percentage of carcass weight), and flock uniformity of the broilers in the second, more unsanitary, experiment. In conclusion, dietary SDPP, fed throughout the growth period, improved growth performance and breast-meat yield of broilers raised in an unsanitary environment.

The Influence of Rearing Light Period and the Use of Broiler or Broiler Breeder Diets on Forty-Two-Day Body Weight, Fleshing, and Flock Uniformity in Broiler Stocks

Feed restriction programs for rearing broiler breeders begin with a period of ad libitum feeding and long day lengths. It is not clear how much early growth rate is limited by light period or nutrient density. This trial was performed to determine the response of full-fed broiler males and females to 4-, 8-, 12-, or 16-h durations of light per day (after 3 d of age), and their responses to broiler or breeder diets. Body weight, feed consumption, mortality, corrected feed conversion ratio, BW uniformity, and carcass characteristics were measured weekly in Ross broiler chicks (800 males and 800 females). At 42 d, the 10 birds per pen closest to the mean BW (total = 320) were studied for external carcass morphometrics (shank length, chest girth and width, and keel length) and breast muscle and abdominal fat pad weights. Body weight uniformity was determined for the individual 42-d BW data.Males were heavier than females, and at 42 d had larger external measurements. However, females had a higher proportion of breast muscle at this time. The variability of 42-d BW of males (CV = 14.2%) was greater than that of females (CV = 12.8%). The 42-d BW of the birds fed the broiler diets was 2.16 kg, on average, compared with 1.79 kg for those fed the breeder diets. Surprisingly, the mean 42-d BW did not increase in direct relationship with light period. The 4-h light period was advantageous for growth and breast muscle yield, when the broiler diets were used. An 8-h light period reduced growth, when the breeder diets were used, while no change was observed with 8 h on the broiler diets. Broiler chicks exposed to 4 h of daylight early in rearing may be highly motivated to consume feed during the dark period. An 8-h light period can slow growth, particularly when breeder diets are used.

A Self-Propelled, Constant-Speed Spray Vaccinator for Commercial Layer Chickens

Vaccination of commercial layer chickens is labor intensive and often results in poor rates of seroconversion, which, in turn, generally correlate with decreased flock uniformity and performance. Attempts to improve the vaccination process include numerous variations of individual shop-built vaccinators in use by the layer sector of the poultry industry. Each of these vaccinators has limitations that contribute to poor vaccinations. Major problems include the nonuniform speed of the applicator system and pressure fluctuations at the spray nozzles, which contribute to sporadic dispersion of the vaccine as the vaccinator is pushed or carried past the cages. A battery-powered, self-propelled, constant-speed vaccinator was designed and constructed that operates with constant nozzle pressure. In field use, this vaccinator has resulted in both labor savings (reduction of manpower from five to one to vaccinate 75,000 chickens) and time savings (from 45 min to 7.5 min/poultry house) as well as improved vaccination results (higher positive seroconversion rates) against the poultry pathogen Mycoplasma gallisepticum (MG), a bacterium associated with losses of 15.7 eggs/hen over a 45-wk laying period in MG-infected layers as compared with layers maintained free from infection with MG.

Performance characteristics and economic comparison of broiler chickens fed wheat- and triticale-based diets

The effects of triticale and wheat on broiler (mixed sexes) performance and cost of production were compared. In experiment 1, wheat- and triticale-based diets were fed to 3 strains of broilers (Ross × Ross, Hubbard x Hubbard, and Ross × Hubbard). Each of the diets was provided to 5 cages/strain (n = 10 chicks/cage; 1,273 cm2/bird). Weekly BW, gain, feed consumption, and feed conversion ratio (FCR; g of feed/g of gain) were determined. At 42 d, 4 chicks/pen were shipped to a commercial processing plant. The plucked, eviscerated carcasses were evaluated for carcass traits. Overall, the triticale-fed birds had lower final BW and average daily gain and higher FCR. Eviscerated carcass, thigh, and drum weights were lower, but pectoralis minor as a percentage of carcass weight was greater in triticale-fed birds. In experiment 2, a wheat diet and a diet in which triticale was substituted (by weight) for wheat were provided in a 3-phase feeding program. Each diet was provided to 2 identically-equipped commercial barns housing 17,034 broilers each. Individual BW of a sample of birds were recorded in each barn at 0, 19, 34, and 42 d, corresponding to the beginning and end of each dietary phase. Feed consumption and FCR were calculated for each barn. An analysis of each of the diets was calculated using a broiler chicken production cost model. Final BW, feed consumption, carcass weight at processing, flock uniformity, percentage of Grade A carcasses, and percentage of condemned carcasses were not affected by cereal source. Overall FCR (2.165, 2.036; P = 0.0052), feed cost ($ 0.617, $ 0.577/kg live weight; P = 0.0260), and total cost of production ($ 1.019, $ 0.972/kg live weight; P = 0.0183) were greater for the triticale than wheat diets, respectively. Triticale would be an economically feasible replacement for wheat in broiler diets when its price is less than or equal to 95% of the cost of wheat, less $ 18 (Canadian). Increased knowledge of the available nutrient profile of triticale, as well as least-cost feed formulation would likely increase the value of triticale relative to wheat for broilers.

Impact of dietary amino acid concentration on growth, carcass yield, and uniformity of broilers

Two studies were conducted to measure the effects of dietary amino acid regimens (high, medium, low) and gender on Arbor Acres Plus broilers. Body weight, feed conversion, mortality, carcass yields, and uniformity served as criteria evaluated. Growth and feed conversion were improved in broilers fed diets with high amino acid concentration until 35 days of age. Yields of some carcass parts were improved up to 35 days of age as diet concentration was increased. Flock uniformity was decreased when dietary amino acid concentration was reduced. Male broilers exhibited faster growth rate, whereas females had improved feed conversion at 28 and 35 days of age, but no differences were observed at 14 and 49 days of age. Male broilers had lower breast meat yield and relative abdominal fat than females. Variability within females was lower than in males. Results indicate that when high dietary amino acid concentration was provided at an earlier age, reducing concentration at later feeding phases did not compromise growth or carcass yields. Furthermore, moderate to high dietary amino acid levels may help reduce variability within flocks.

Effect of Physical Feed Restriction During Rearing on Large White Turkey Breeder Hens: 1. Growth Performance

Large White turkey breeder hens were fed ad libitum (CC), feed-restricted from 16 to 24 wk (CR), feed-restricted from 3 to 16 wk (RC), or feed-restricted from 3 to 24 wk (RR). Feed restriction was implemented so that RC and RR hens achieved a 45% reduction in BW compared to CC hens at 16 wk. From 16 to 24 wk, feed was allotted to RR and CR hens to maintain a slight increase in BW. At the completion of each restriction period, hens were gradually released back to ad libitum feeding. At 30 wk of age, hens were photostimulated for a 20-wk summer season egg production cycle. Mean BW for all treatments were different (P ≤ = 0.05) at 16 and 30 wk. At the end of lay, hens on treatment CR were not different in BW from treatment CC hens, and treatment RR hens were not different in BW from treatment RC hens. Hens on treatment RR had the greatest BW gain and feed consumption leading into the production cycle. All treatment hens lost BW from the time of first egg until 47 wk of age. Hens on treatment CC lost significantly (P ≤ = 0.05) more relative BW (%) than those in any other treatment. Coefficient of variation for flock uniformity was similar for all treatments at time of photostimulation. At the end of the study, cumulative feed consumption was significantly less for restricted treatments: 86.5, 83.1, 75.8, and 70.7 kg/hen for treatments CC, CR, RC, and RR, respectively.

Effects of age at photostimulation on reproductive efficiency and carcass characteristics. 1. Broiler breeder hens

The effect of age at photostimulation on carcass composition at photostimulation and at sexual maturity as well as its effect on subsequent reproductive performance in broiler breeders was investigated. A total of 600 broiler breeder pullets were reared in light-tight facilities. Skip-a-day feeding was used after 2 wk of age to limit body weight to levels suggested by the breeder. Limited daily feeding was initiated at the time of caging (time of photostimulation). The photoperiods used during rearing and lay were 8L:16D and 14L:10D, respectively. Forty birds were selected for study and moved to laying cages and photostimulated at 120, 130, 140, 150 or 160 d of age. Individual egg production records were kept until 60 wk of age. Twenty additional birds were killed for study of carcass composition and reproductive organ, morphology at the time of photostimulation and 20 others were killed at sexual maturity (first oviposition).As age at photostimulation increased, body weight and percent carcass lipid content increased while percent water and ash content decreased. No significant differences were found among treatment groups at photostimulation for carcass protein content. No significant differences were found in any carcass composition parameter at sexual maturity. All groups showed an increase in lipid content from photostimulation to sexual maturity, with the 120 d treatment group showing the largest increase. As age at photostimulation increased, the time from photostimulation to sexual maturity decreased. Total egg production, first egg weight, total egg mass produced, average fertility, hatchability and hatch of fertile did not differ significantly among treatment groups. Chick production was significantly higher in the 140-, 150- and 160-d treatment groups compared with the 120- and 130-d treatment groups. One explanation for the high rate of egg production seen in birds photostimulated at the older ages was that these birds reached sexual maturity with less between-bird variation. To take advantage of this improved flock uniformity, delaying photostimulation to 140 d of age or later is recommended. Key words: Chicken, broiler breeder, sexual maturity, egg production, hatchability, carcass composition

Mathematical Curves for the Description of Input and Output Variables of the Daily Production Process in Aviary Housing Systems for Laying Hens

The objectives of this study were 1) to compute appropriate mathematical curves that describe the daily production process by the input variables daily feed consumption, water consumption, ambient temperature, and output variables hen-day egg production, egg weight, second grade eggs, floor eggs, cumulative mortality, body weight, and flock uniformity; and 2) to obtain insights into the daily variations in these variables, in order to support the poultry farmer with an aviary housing system in his daily management. Literature and research data attainted from six unmolted flocks that were housed in aviary systems were used to formulate the mathematical curves. The curves were a function of the number of days in the laying period. Curves for cumulative mortality, hen-day egg production, egg weight, body weight, and percentage of floor eggs described individual flock results well (0.72 < R2adj < 1.00). The coefficients of determination for feed consumption, water consumption, flock uniformity, and percentage of second grade eggs were in general low (0.33 < R2adj < 0.54), which implies that the form of the curve differs between flocks. Egg weight, body weight, cumulative mortality, and hen-day egg production had the lowest minimum coefficients of variation (0.8 to 1.9), followed by feed consumption, water consumption, and flock uniformity (2.8 to 3.6). Ambient temperature, percentage floor eggs, and percentage of second grade eggs had the highest minimum coefficients of variation (4.8 to 9.1).

The Effects of Nutrient Dilution on the Well-Being and Performance of Female Broiler Breeders

A study was conducted to determine the effect of nutrient dilution on plasma heterophil:lymphocyte ratios, behavior, and productivity of broiler breeder hens. Standard age-appropriate broiler breeder diets were fed either undiluted or diluted with 15 and 30% ground oat hulls from 0 to 56 wk of age. Feed was allocated daily so as to achieve the BW recommended by the breeder. Pullets were photostimulated at 20 wk, at which time 80 per treatment were moved, 2 per cage, to 120 laying cages, where they were housed until 56 wk of age. The same dilution treatment was continued for the laying period.The time required to consume the diluted feed was higher when diets were diluted during both the rearing (P = .002) and the laying periods (P = .0001). Heterophil:lymphocyte ratios at 12 wk of age indicated that hens subjected to higher levels of quantitative feed restriction experienced more long-term stress (P < .05). This difference was not evident at 20 wk or at 50 wk. During the laying period, hens that were fed diluted diets spent less time at the water source than those fed standard diets (P = .0001). The rate of decrease in flock uniformity during lay was slower in hens fed the diluted diets (P < .05). Hens fed the diet diluted by 15% had the highest egg production (P = .012), chick production (P < .0001), the best CP conversion efficiency (P < .05), and better feed conversion efficiency (P < .05). Diet dilution with ground oat hulls seems to be a means of reducing stress and improving efficiency and productivity in broiler breeder flocks.

The Use of Feed Restriction for Improving Reproductive Traits in Male-Line Large White Turkey Hens.: 1. Growth and Carcass Characteristics

The influence of feed allowance during rearing was investigated in male-line Large White breeder hens. A flock of 200 poults was reared from 4 to 28 wk of age under four treatments as follows: full-fed controls (FF), lowprotein diet (12% CP from 12 to 28 wk; LP), and reduced BW (10 or 20% lower BW than FF; R10 and R20). At photostimulation (28 wk), all birds consumed a commercial breeder diet ad libitum for the remainder of the study (48 wk of age).Body weight differed among treatments during most of rearing. The LP birds were similar in BW to the R10 birds at 28 wk of age. By 40 wk of age, growth curves of all treatments became similar, with the R20 group having lower BW. Feed restriction reduced frame size during rearing. Flock uniformity in the R10 and R20 treatment hens was reduced during rearing, but improved early in the breeder period. Feed restriction reduced breast muscle and abdominal fat pad weight early in lay, except for the LP group. Liver lipid content increased throughout the breeder period. Changes in liver weight followed the pattern of BW changes. Total carcass protein content changes in time reflected breast muscle mass changes. In R20 hens, carcass lipid content was reduced and protein content increased. Sexual maturity was delayed in the R20 hens. Body weight at first egg was negatively correlated with settable egg production (r = –.37, P ≤ .0015). The R20 treatment is recommended for male-line turkey breeder hen candidates during rearing.

Strategies for Weighing Broilers, Broiler Breeder Pullets and Broiler Breeder Hens: 1. Sample Size and Individual vs. Group Weighings

Evaluations were made of the effects of sample size and individual vs. group weighing of broiler and broiler breeder stock on the estimation of body weight gain and uniformity. Results indicated that suspected outliers should not be rejected from the sample. Group weighings are satisfactory to determine average body weight, but individual weights are necessary for flock uniformity estimates. Average body weight and flock uniformity estimates were satisfactory when obtained by weighing all birds in a penned-up sample and using a total bird count approximating at least 1% of the flock size.

Strategies for Weighing Broilers, Broiler Breeder Pullets and Broiler Breeder Hens: 2. Scale Type, Weighing Time and In-House Location

The effects of in-house sampling locations, type of scale, and time of weighing on apparent mean body weight, body weight gain and uniformity were determined for broiler and broiler breeder stock. Deviations in time of weighing were shown to be an important source of error when estimating live weight gain. No significant differences were detected in average body weight due to scale type. A significant location effect was found with breeder hens, but not with broilers or broiler breeder pullets. A balance between accuracy and efficiency of a weighing program can be maintained when average body weight and flock uniformity estimates are derived by sampling one in-house sampling location, using an electronic or a spring scale, and conducting weighings at the same time during each weigh period.

Feed Restriction in Broiler Breeder Pullets: Skip-a-Day Versus Skip-Two-Days

Effects were compared of two methods of feed restriction (skip-a-day, SAD, vs. skip-two-days, STD) during 4 to 22 wk of age on the development, uniformity, and subsequent performance of White Rock pullets. The pullets, housed in cages, consumed the same amount of feed in both treatments. Nevertheless, body weights of birds kept under the STD feeding regimen were significantly (P<.01) lower. This difference was still significant (P<.05) at 35 wk of age. Flock uniformity at 11 wk of age was significantly (P<.05) higher in pullets kept on the STD feeding program.Plasma glucose and corticosterone levels in fasted pullets and corticosterone levels in fed birds at the age of 21 wk were not affected by feeding regimen. However, the increase in plasma glucose after feeding was significantly (P<.05) higher in pullets on the STD feeding program. Plasma corticosterone levels were consistently, and at times significantly (P<.05), higher in fasted birds.Laying of the first egg was significantly (P<.05) delayed in hens previously kept on the STD feeding regimen. Rate of egg production and egg weights up to 35 wk of age were not affected by the method of feed restriction.

Effects of Early Maturation of Brown Egg-Type Pullets, Flock Uniformity, Layer Protein Level, and Cage Design on Egg Production, Egg Size, and Egg Quality

Eight-week-old Harco Sex-Link pullets were assigned to four growing regimens. Feed was restricted to Group 1. The birds reached an average weight of 1.52 kg at 20 weeks of age and were then light stimulated. Group 2 received the same ration ad lib and reached an average weight of 1.64 kg at 16 weeks. At this age they were light stimulated. Birds in Groups 3 and 4 were separated into two weight classes at 8 weeks of age. Those below the median weight received an 18% protein grower ration and those above the median weight a 16% ration. Group 3 birds were grown similarly to Group 1; Group 4 birds were grown similarly to Group 2. At housing, each group was equally divided and given either a 17 or 19% protein layer ration. Two cage designs (standard and reverse) were used and each treatment combination was equally represented. Ad lib-fed, early-housed pullets reached 1.64 kg at 16 weeks of age, but they did not come into production until 19.4 weeks of age. Hen-day percent production (HDP) was significantly less than for the late-housed pullets. Feed per dozen eggs was not affected by the early housing, but early-housed pullets laid significantly smaller eggs and feed per gram egg was significantly increased. Hens in reverse cages on a 19% protein layer ration laid the largest eggs in weight and size. Although early housing had a detrimental effect on average egg weight, it appeared possible to manipulate egg weight and size distribution through a combination of cage design and layer protein.Birds grouped by body weight at 8 weeks had higher uniformity, but this trait was not correlated with egg numbers or size. Moreover, housing body weights were not significantly correlated with egg size, suggesting factors other than body weight were responsible for the smaller eggs from early-housed pullets.

The Influence of Flock Uniformity on the Reproductive Performance of Broiler Breeder Hens Housed in Cages and Floor Pens

Two flocks of broiler breeder hens, differing in uniformity of body weight, were evaluated under cage and floor management systems over a 28-week period. Hens were housed singly in cages (N = 280) or in litter floor pens (N = 304). Caged hens were artificially inseminated with .05 ml of pooled semen once weekly. Floor birds were mated naturally. During the first 10 weeks of production, the more uniform flock exhibited significantly higher egg production than the less uniform flock. Uniformity did not influence cumulative egg production, egg weight, fertility, or mortality. Initial egg production was similar for caged and floor housed hens, but the caged birds attained significantly higher egg production during peak production. Caged females showed higher egg weights and body weights than did the floor females throughout the study. Naturally mated birds attained significantly higher fertility than artificially inseminated birds (94.9 vs. 90.6).Correlation coefficients for the weights of caged hens at 20 and 24 weeks with 24, 32, 40, and 50 week weights, total eggs per bird, and age at first egg indicated that body weight at 24 weeks was a better indicator of subsequent flock performance than was body weight at 20 weeks.

Control of Flock Uniformity of Broiler Breeder Pullets Through Segregation According to Body Weight

Broiler breeder replacement stock was housed in six floor pens with 100 females and 15 males per pen. All birds were fed an 18% protein starter ration and grown under the same management conditions to 4 weeks of age. At 4 weeks, 300 females were weighed and divided into three groups consisting of the heaviest, middle, and lightest birds. These three groups were designated the treatment flock and were fed 13%, 15%, and 17% protein rations, respectively. The remaining 300 pullets were divided according to body weight in the same manner and fed a 15% protein ration throughout the growing period. These birds were designated as the control flock. Both flocks were fed according to a skip-a-day regimen and provided with 12 hr of light. At 8, 12, and 16 weeks, both flocks were weighed, rearranged according to body weight, and fed the ration appropriate as outlined above.The average body weight of the two flocks at 4, 8, 12, 16, and 20 weeks did not differ from each other by more than 44 g. Both flocks averaged 2.4 kg at 20 weeks of age. The treatment flock exhibited higher degrees of uniformity than the control flock from 8 to 20 weeks of age. The difference in uniformity was attributed to the feeding of a high protein diet to the light birds and a low protein diet to the heavy birds. It was concluded that the method of segregating broiler breeder pullets according to body weight as a part of a restricted feeding program can result in a more uniform flock at 20 weeks of age.

Fundamental Principles of Broiler Breeders Nutrition and the Design of Feeding Programmes

SummaryThe design of feeding programmes for broiler breeders and the fundamental principles on which they should be based are discussed with emphasis on the practical aspects under field conditions. Feed restriction is deemed to be essential from a relatively early age if the performance of the modern broiler breeder is to reach the potential of which it is capable. Control of the growth rate can only be achieved, without undesirable consequences, if feeding programmes are carefully planned and efficiently and intelligently applied throughout the rearing and laying periods. Three points are considered vital to the economic success of a flock. 1) the body weight at point-of-lay and the manipulation of the rate of growth in order to reach it without impairing flock uniformity.2) the synchronization of growth and sexual maturity and3) accurate feeding at Start of production and during the peak period. Feeding programmes and management procedures are suggested to enable breeding flocks to perform their maximum potential. The advice is presented in a practical manner to serve as a guide to poultry advisers and managers of broiler breeding flocks in particular.

Growth performance and uniformity of commercial brown layer chicks

Growth performance of commercial brown layer chicks (Shaver 579; n = 408) was studied in an open-sided house by feeding layer starter and layer grower diets during 0-17 weeks of age. The experimental period was divided into three phases: Phase I (0-4 weeks), Phase II (5-7 weeks) and Phase III (8-17 weeks). Both growth and feed consumption closely followed the standard data except during 10, 11, 12 weeks of age when the birds had to face some stresses. The target body weight was 1.4 kg which was achieved at proper age (17 weeks) by consuming feed almost similar to standard amount. Compensatory growth of chicks occurred during the later stage of growing period. The flock uniformity was 80% at 17 weeks. Livability of chicks was found to be excellent (99.3%) during the experimental period (0-17 weeks). It is suggested that despite some stresses, commercial brown layer chicks may achieve body weight and uniformity close to breeder’s standards when reared in an open-sided house. Key words: Growth; Uniformity; Commercial brown layer DOI: http://dx.doi.org/10.3329/bjas.v39i1-2.9691 Bang. J. Anim. Sci. 2010, 39(1&amp;2): 170-175