Effect of method and phase of nutrient restriction during rearing on productive performance of light hybrid pullets and hens

Influence of the energy concentration and the standardized ileal digestible lysine content of the diet on performance and egg quality of brown-egg laying hens from 18 to 41 weeks of age

The influence of the energy and the standardized ileal digestible lysine (DLys) content of the diet on egg production and egg quality, was studied in brown-egg laying hens from 18 to 41 wk of age. The experimental design was completely randomized with 10 treatments organized as a 2 × 5 factorial with 2 energy concentrations (2,750 and 2,800 kcal AMEn/kg) and 5 levels of DLys (values varied from 0.66 to 0.78% and 0.67 to 0.79%, for the low and high energy diets, respectively). Each treatment was replicated 10 times (10 hens per replicate). The data were analyzed using the MIXED procedure of SAS with energy concentration and DLys content of the diets as main effects. In addition, the effects of the DLys on the variables studied were partitioned into its lineal and quadratic components. From 18 to 21 wk of age (pre-peak phase), diet composition had limited effects on egg production. From 22 to 41 wk of age (peak phase), however, an increase of 50 kcal AMEn/kg diet increased egg weight (P < 0.05) and tended to improve energy intake (P = 0.083) and feed conversion ratio (P = 0.074). An increase in DLys improved linearly (P < 0.001) egg production, egg weight, egg mass, feed conversion, and energy conversion ratio, and tended to increase BW gain (P = 0.074). Diet composition did not any affect egg quality trait except shell strength that increased linearly (P < 0.05) with increases in the DLys. Cumulatively (18–41 wk of age), egg weight increased (P < 0.05) as the energy and the DLys content of the diet increased. In summary, an increase in energy and DLys content of the diet had limited effects on egg production during the prepeak phase but improved egg production, feed conversion ratio, and BW gain during the peak phase. The data indicate that hens require at least 839 mg DLys/d to maximize egg production in the peak production phase.

The effect of rearing photoperiod on broiler breeder reproductive performance depended on body weight

Body weight (BW) and rearing photoperiod are important factors affecting sexual maturation rate and reproductive performance in broiler breeders. The current experiment used a 2 × 3 factorial arrangement of treatments to study the interaction between BW and rearing photoperiod on reproductive performance in group housed broiler breeder hens, while minimizing variation in BW. Hens (n = 180) were fed with a precision feeding system to allocate feed individually to achieve the breeder-recommended target curve (Standard) or to a target curve that reached the 21 wk BW at 18 wk (High). Hens were on 8L:16D, 10L:14D, or 12L:12D photoschedules during rearing and were photostimulated at 21 wk with a 16L:8D photoschedule. Sexual maturity (defined as age at first egg) and individual egg production to 55 wk were recorded. At 55 wk, proportional weights of individual body components were determined by dissection. Differences were reported as significant at P ≤ 0.05. A significant interaction between BW and rearing photoschedule affected age at sexual maturity and egg production. In the High BW treatment, age at sexual maturity did not differ between hens under the 8L:16D and 10L:14D photoschedules (173 vs. 172 d, respectively). In the Standard BW treatment, the 12L:12D rearing photoperiod delayed sexual maturity compared with the 8L:16D rearing photoperiod (266 vs. 180 d, respectively). All hens on the High BW treatment laid at least 1 egg before the end of the experiment. Conversely, 3.3, 18.1, and 37.6% of Standard BW hens on the 8L:16D, 10L:14D, and 12L:12D photoschedules, respectively, never commenced egg production. At the end of the experiment, proportional breast weight was higher and proportional fatpad weight was lower in Standard compared to High BW hens (25.8 vs. 27.5% and 2.4 vs. 1.5% of BW, respectively). We conclude that increased BW partially counters the effect of longer photoschedules on sexual maturity in broiler breeders and that dissipation of the photorefractory state depends on BW.

EXIGÊNCIA DE METIONINA + CISTINA PARA FRANGAS DE REPOSIÇÃO NA FASE INICIAL (1 A 6 SEMANAS DE IDADE)

Resumo Objetivou-se determinar a exigência de metionina + cistina total para frangas na fase inicial e verificar seu efeito sobre a fase de postura. Na primeira fase experimental, 720 aves (50% Lohmann LSL e 50% Lohmann Brown) com uma semana de idade foram distribuídas em delineamento experimental inteiramente casualizado, em esquema fatorial 5 x 2 (níveis de met + cis e linhagens), com quatro repetições e 18 aves por repetição. Os níveis de met + cis total estudados foram 0,536; 0,616; 0,696; 0,776; e 0,856 %. Ao atingirem 22 semanas de idade, iniciou-se a segunda fase experimental, sendo utilizadas 240 aves (50% Lohmann LSL e 50% Lohmann Brown) provenientes da primeira fase experimental. A ração fornecida às aves nesta fase foi igual para todos os tratamentos. Na fase de produção avaliaram-se os efeitos residuais das dietas fornecidas no período inicial sobre os parâmetros produtivos. As exigências de metionina + cistina recomendadas para aves leves e semipesadas, no período de 1 a 6 semanas de idade, são de 0,778% de met + cis total (correspondendo a 0,700% de met + cis digestível) e 0,739% de met + cis total (correspondendo a 0,665% de met + cis digestível), respectivamente.

Responses of organic housed laying hens to dietary methionine and energy during a summer and winter season

1. The main dietary challenge in organic laying hen production is to fulfil the digestible methionine (MET) requirement in a diet consisting of ingredients of organic origin only. 2. The aim of the present experiment was to determine the response of organic housed laying hens (26-34 weeks of age) to dietary energy and MET during a summer and winter trial. Per trial, a total of 128 17-week-old Brown Nick hens were allotted to 16 pens, which were connected to an outdoor run. Each experiment comprised 8 dietary treatments according to a 4 × 2 factorial design. The factors were AFD MET level (2.3, 2.7, 3.1 and 3.5 g/kg) and energy content (10.9 and 12.1 MJ). 3. Dietary energy content did not affect energy intake (1361 kJ/d) in summer, whereas energy intake in winter was increased in hens that were fed on the 12.1-MJ diets (1514 vs. 1421 kJ/d). Maximal egg mass in summer was achieved if a diet with 3.5 g/kg MET was given, corresponding to a digestible MET intake of 421 mg/d. During winter, maximal egg mass was achieved with a digestible MET intake of 360 mg/d, which was already realised with a MET content of 2.7 g/kg. 4. Because digestible MET content for maximal egg performance differed between the summer and winter trial, dietary energy to MET ratio might be adjusted to seasonal conditions.

Exigência de metionina + cistina para frangas de reposição na fase cria de sete a 12 semanas de idade

Determinou-se a exigência de metionina + cistina para frangas de sete a 12 semanas de idade e verificou-se seu efeito sobre a fase de postura. O experimento foi dividido em duas fases, de cria e de produção, esta de 22 a 33 semanas de idade. Na primeira fase, utilizaram-se 640 aves - 50% Lohmann LSL e 50% Lohmann Brown - com sete a 12 semanas de idade, distribuídas em delineamento inteiramente ao acaso, em esquema fatorial 5x2 (porcentagem de met+cis e linhagem), com quatro repetições e 16 aves por repetição. As porcentagens de met+cis total estudadas foram 0,471; 0,541; 0,611; 0,681 e 0,751%. Ao atingirem 22 semanas de idade, 240 aves foram utilizadas para verificar o efeito residual das dietas fornecidas na fase de cria. A dieta fornecida nesta fase foi igual para todas as aves. As exigências de metionina + cistina para aves de reposição, leves e semipesadas, no período de sete a 12 semanas de idade, foram de 0,710 % de met+cis total (0,639% de met+cis digestível) e 0,706% de met+cis total (0,635% de met+cis digestível), respectivamente.

Exigência de metionina + cistina para frangas de reposição na fase recria de 13 a 18 semanas de idade

Determinou-se a exigência de metionina + cistina para frangas de 13 a 18 semanas de idade e verificou-se seu efeito sobre a fase de postura. O experimento foi dividido em duas fases experimentais, recria e postura. Na fase de recria, 560 aves - 50% Lohmann LSL e 50% Lohmann Brown -, com 13 a 18 semanas de idade, foram distribuídas em delineamento inteiramente ao acaso, em esquema fatorial 5x2 (porcentagem de met+cis e linhagens), com quatro repetições e 14 aves por repetição. As porcentagens de met+cis totais estudadas foram 0,399; 0,469; 0,539; 0,609 e 0,679%. Ao atingirem 22 semanas de idade, 240 aves foram utilizadas para se avaliar o efeito residual das dietas oferecidas na fase de recria sobre o desempenho das aves, a produção e a qualidade de ovos. Ao se considerar a fase de produção, não se verificou efeito da inclusão de níveis de met+cis na ração, para ambas as linhagens. As exigências de metionina + cistina totais foram de 0,679% (0,611% de met+cis digestível) para aves leves e de 0,646% (0,581% de met+cis digestível) para aves semipesadas.

The effect of low-density diets on broiler breeder development and nutrient digestibility during the rearing period

Low-density diets might help to reduce hunger feeling in restricted-fed broiler breeders. Effects of low-density diets on nutrient digestibility and bird development were studied in Cobb 500 broiler breeder hens from 4 wk of age until the onset of the lay (wk 26). The experiment included 4 treatments. The control treatment was a normal density diet (ND; 2,600 kcal/kg). Treatments 2 and 3 had a 12 and 23% lower nutrient density than ND (LD12 and LD23, respectively) through inclusion of palm kernel meal, wheat bran, wheat gluten feed, and sunflower seed meal. Treatment 4 also had a 12% lower nutrient density than ND but included oats and sugar beet pulp (LD12(OP)). Total daily intake of energy, digestible lysine, calcium, retainable phosphorus, sodium, and linoleic acid was kept constant in the low-density dietary treatments. Animal performance and development of the intestinal tract and reproductive tract were determined in addition to digestibility and feed passage rate. The LD12(OP) provided a lower AME and nutrient digestibility than calculated and was related to lower live weights. Birds given LD23 and LD12(OP) showed a faster ovarian and oviduct development between wk 24 and 26 compared with ND. At 22 wk of age, LD23 and LD12(OP) diets resulted in higher empty jejunum and ileum weights. Low-density diets did not affect intestinal tract contents and decreased mean retention time of the contents. It was concluded that low-density diets can affect live weight and development of digestive and reproductive tracts.

The Effect of Low-Density Diets on Broiler Breeder Performance During the Laying Period and on Embryonic Development of their Offspring

The effect of low-density diets on bird performance, egg composition, and embryonic development was studied with 2,100 female and 210 male Cobb broiler breeders from 25 to 60 wk of age. The experiment included 5 treatments. These included a control group with a normal density diet (ND, 2,800 kcal of AME/kg). Treatments 2 (LD11) and 3 (LD21) had a 11 and 21% lower nutrient density. Treatment 4 (LD11(OP)) had a 11% less dense diet, which was obtained by inclusion of other feed ingredients. In these 4 treatments similar diets were given during the rearing and the laying period. Treatment 5 combined LD12 in the rearing period and ND diets during the laying period (LD12-ND). Egg composition and embryonic development were measured in eggs of ND and LD21 birds at 29 and 41 wk of age. During the laying period from wk 25 to 60, live weights did not differ among treatments, except that birds fed LD11(OP) had lower live weights. A significantly higher rate of lay was provided by LD11 compared with ND. Egg weights were significantly higher when low-density diets were fed, particularly in LD11(OP). Percentage of fertile eggs did not differ among treatments. Compared with the other treatments, LD11(OP) provided a significantly lower hatchability. We found that LD21 resulted in a better development of the area vitellina externa and heart and embryo weight at 29 wk of age. It was concluded that this was related to a higher egg weight and egg white proportion. This suggests that the amount of egg white in eggs of hens fed ND was limiting for embryonic development, particularly in eggs of young broiler breeders.

Diphasic allometric growth of some skeletal bones and the digestive tract in White Leghorn pullets consuming ad libitum and restricted diets

Growth data of some bones (shank, tibia, and keel) and the digestive tract in White Leghorn pullets, which consumed ad libitum and restricted diets, were analyzed by mono- and diphasic allometric functions. Fat-free plucked empty body mass (FFEBM) or a functional entity was used as the independent variable in the equations. Pullets had been fed a low-lysine diet or a daily restricted amount of an adequate diet, from 0 to 6 or 7 to 18 wk of age. An additional group of pullets consumed ad libitum a control starter and grower diet. Relative growth of the skeletal bones and parts of the digestive tract, vs FFEBM, was described most accurately by a diphasic model. For each constituent, allometric slopes of the first growth phase (beta1) vs FFEBM were smaller than 1 (beta1 varied from 0.39 to 0.43 for shank and tibia, from 0.48 to 0.73 for the keel, from 0.89 to 0.98 for the total digestive tract, and from 0.80 to 0.84 for the gizzard, separately). These results suggest that each of the assessed organs matured earlier than the FFEBM. Except for the keel, which grew relatively faster than FFEBM if an early nutrient restriction had been applied, beta1 of all other assessed structures was similar for all treatments. If the allometric slope of the second growth phase (beta2) was estimated to be not different from zero, then the breakpoint between both phases was defined as the moment of attainment of maturity for the respective constituent. The attainment of maturity of the different body structures confirmed the classical growth sequence studies of the Hammond School. No differences in mature weights for the assessed organs between the feeding regimens were observed. The results indicated that in studies in which a nutritional deficiency had been applied, the weights of several body structures, most often expressed in terms of weight per 100 g BW, are strongly related to the decrease in growth rate of the fat-free body. It was concluded that most of the reported effects on growth retardation as a result of nutrient restrictions are primarily a consequence of the mobilization of fat per se.

Food restriction and development of thermoregulation in Muscovy ducklings (Cairina moschata)

1. The interaction between the effects of food restriction and cold stress on the development of body temperature, homeothermy index, metabolic rate and body weight were studied in Muscovy ducklings from hatching to 21 d of age. 2. The control group (ad libitum fed) and the food restricted group (fed to zero growth rate for 9 d) both became homeothermic when they were 2 d old with moderate (10 degrees C) cold stress. At severe cold stress (0 degrees C) the control group was homeothermic 5 days after hatching. However the food restricted group did not reach homeothermy at 0 degrees C and showed a large decrease (to hatching level) in homeothermy index at 10 degrees C and 0 degrees C after 9 d of food restriction. 3. Body temperature was lower in the food-restricted group during restriction and increased by 1 degree C after 24 h of ad libitum feeding. During food restriction, resting metabolic rate did not increase with age and was lower than the basal and existence metabolic rate predicted by Aschoff and Pohl (1970) and Kendeigh (1970) respectively. 4. The ratio of metabolisable energy (ME) intake to resting metabolic rate was 3 times lower in the food-restricted group than in the control group (0.09 and 0.27 respectively) on day 9. The availability of ME was more important than age for the development of thermoregulation in Muscovy ducklings. It is concluded that small improvements in the feeding regimen of young ducklings enhance the endurance and consequently reduce mortality from to environmental cold stress in a scavenger poultry system.

Diphasic allometric growth of body components in white Leghorn pullets fed ad libitum and restricted diets

Growth patterns of crude fat (cfat; ether extract), CP, ash, and water in White Leghorn pullets that ate ad libitum and restricted (feed or lysine) diets were analyzed by mono- and diphasic allometric functions, with plucked empty body mass (EBM) or fat-free EBM (FFEBM) as the independent variates. In general, the diphasic model provided a better fit to the data than the monophasic model, indicating that the allometric slope (beta) changes at a certain level of development. Data demonstrate that, under an ad libitum feeding regimen, cfat growth is proportionally (beta = 1) related to growth of the fat-free body, up to about 500 g FFEBM (pullets aged 8.5 wk). From 500 g FFEBM onwards, the beta changed to about 2, illustrating the late maturation of cfat compared to FFEBM. For feed-restricted groups, slopes and transitions for cfat growth varied from those of the control group, according to changes in dietary supply. Diphasic relationships between each fat-free body component and EBM in each treatment had different slopes for first and second phases (about 1 and 0.70). Differences, however, were mainly due to the diphasic growth pattern of cfat per se, and diminished largely if FFEBM instead of EBM was chosen as the independent variable (about 1 and 0.95). Incorrect statements on body component growth in restricted birds, due to the "masking" role of varying fat deposition rates, can be avoided if relative growth was expressed as a function of the fat-free body instead of BW or EBM. Diphasic growth relationships among the fat-free body components were not affected by feeding regimen, but by age. The beta 1 were about unity for the relationship between each fat-free component and FFEBM, suggesting a constant composition of the fat-free body in the first phase. In the second phase, CP accrued relatively faster than ash and water (beta 2 of 1.10 vs 0.94 and 0.91). Results indicate that the changes in growth pattern of fatty and fat-free tissue, both relative to the fat-free body, had not been revealed if a monophasic allometric model instead of a diphasic had been used.

Onset of lay related to multiphasic growth and body composition in White Leghorn pullets provided ad libitum and restricted diets

Growth of the body as a whole and of parts of the reproductive tract of White Leghorn pullets that ate ad libitum and restricted diets were analyzed by a multiphasic growth function. Parameter estimates were related to onset of lay. Chemical body compositions at defined stages of pubertal growth were related to the development of the reproductive organs. Data of pullets that had been restricted in one of two rearing periods (0 to 6 and 7 to 18 wk of age) were used. In each period, pullets were fed a low-lysine diet or a daily restricted amount of feed, on a pair-gain basis. In all mathematical fits, a well distinguishable "pubertal body growth spurt" at around 19 wk of age was found. About 40 to 70% of total growth within this phase consisted of growth of the reproductive tract (the ovary covered 19 to 35%, the oviduct 15 to 23%, and the uterus 7 to 11% of total growth). Age at maximum gain of the pubertal body growth spurt was 20.1 wk for lysine-restricted pullets and 19.6 wk for feed-restricted pullets. This difference reflected differences in onset of lay (50% rate of lay) between lysine- and feed-restricted birds (22.3 and 21.6 wk, respectively). An interval of 14 to 15 d existed between maximum gain of the pubertal body growth spurt and onset of lay. It was suggested that the occurrence of the pubertal body growth spurt can serve as a predictor for subsequent onset of lay. Body composition at defined moments during the pubertal body growth spurt was calculated by interpolation from chemical analyses of Weeks 15, 18, 20, 22, and 24. Crude fat content in the body at start of the pubertal body growth spurt varied considerably between the feeding regimens (112 to 179 g). The fat-free body (consisting of CP, ash, and water) showed less variation between the treatments at this stage (807 to 870 g). It is concluded that a particular amount of fat-free tissue is critical in pullet development and may be required before sexual organ development starts.

The effect of dietary manipulations of energy, protein, and fat during the growing and laying periods on early egg weight and egg components

Two experiments were conducted to determine the effect of dietary energy, protein, and fat during the latter parts of the growing period and the early parts of the laying cycle on early egg weight and egg components. In Experiment 1, pullets were fed diets containing two levels of energy (2,816 and 3,036 kcal ME/kg), two levels of protein (14 and 18%), and two levels of fat (0 and 4%) in factorial arrangement from 14 to 18 wk of age. From 18 to 34 wk of age, pullets from all of the growing regimens were fed a 16.5% protein diet. In Experiment 2 (18 to 34 wk of age), six diets were used. The energy, supplemental fat, and protein content of the diets were: T1:2,816 kcal/kg, 0%, 17%; T2:2,816 kcal/kg, 0%, 21%; T3:2,816 kcal/kg, 4%, 17%; T4:2,816 kcal/kg, 4%, 21%; T5:3,036 kcal/kg, 4%, 17%; and T6:3,036 kcal/kg, 4%, and 21%. The data were analyzed factorially with energy constant and fat and protein variable (T1 to T4) and with fat constant and energy and protein variable (T3 to T6). In Experiment 1, 18-wk body weight increased slightly (P < .05) due to increasing the energy or adding fat to the diets, whereas egg weight during the early stages of egg production was increased modestly (P < .05) only due to increasing the energy level. In Experiment 2, when energy was constant, egg weight was increased due to increasing the protein level or adding fat to the diets (P < .05). When fat was constant, egg weight was increased only due to increasing the protein level (P < .05). The increased egg weight under these conditions was due mainly to increasing the albumen weight. The results indicated that egg weight during the early stages of the egg production cycle can be increased due to increasing the protein level from 17 to 21% or by adding 4% fat to the conventional layer diets, and that the beneficial effect of fat on egg weight is independent from its energy effect.

Multiphasic analysis of growth of the body and its chemical components in White Leghorn pullets

Data of White Leghorn pullets consuming feed ad libitum were used to study multiphasic growth during rearing and early lay. Two mathematical functions were used. Body weight gain and growth of the chemical components DM, CP, crude fat (Cfat), and ash (Ash) were described as a function of age, using a multiphasic growth function. To describe relative growth between CP and DM, Cfat and DM, and Ash and DM, a multiphasic allometric function was applied. Body weight gain from hatching to 24 wk of age was estimated most accurately by a tetraphasic growth function. The first two growth spurts represented 82% of mature BW. Growth in these two phases seemed to be related to the development of bones, muscles, and essential metabolic organs. Body growth was further characterized by a third phase at 19 wk of age, which was related to growth of the reproductive tract. The fourth phase consisted mainly of body fat deposition. Both multiphasic functions showed that the nature of component growth was diphasic, with a transition area between the two phases at around 11 wk of age. On the basis of the duration of growth and of allometric growth coefficients, growth of CP, Cfat, and Ash in the first phase seemed to be functionally related to each other and consisted of muscle growth, intermuscular fat deposition, and skeletal growth, respectively. After 11 wk of age, protein deposition is presumably a function of sexual maturity, i.e., the development of the reproductive tract; whereas fat growth is mainly abdominal fat deposition. The observed relationships indicate that the use of multiphasic functions might be helpful in the interpretation of changes in body growth and development of pullets.