Prelay Diets Research Articles

Efficacy of Best Prelay Diet on Production Performance of White Leghorn Layers Fed with Different Layer Diets

Background: Feeding high nutrient density best prelay diet (BPD) 2-3 weeks before egg production is beneficial and may allow to reduce layer diet nutrient density. Methods: Total 180, 16-week-old White Leghorn pullets were assigned to six-layer feeding strategies (kcal ME per kg/%CP/%Ca) during 19-40 weeks. Treatments were T0 (BIS control-2600/18.0/3.0), T1 (2500/18.0/3.0), T2 (2500/18.0/4.0), T3 (2500/17.0/4.0), T4 (2500/16.0/4.0) and T5 (2500/15.0/4.0). These layers were fed with same BPD (2700/18.0/2.5) during 16-18 weeks. Performance parameters were recorded during the study. Result: Feeding BPD did not influence pullets (16-18 woa) CaI, PI and MEI. The 3.0% layer Ca (T0 and T1) decreased (p less than 0.01) CaI than 4.0% (T2 to T5) and layer diet CP reduction from 18.0 to 15.0% decreased PI but 2500 or 2700 kcal ME/kg layer diet did not affect MEI (19-40 woa). BPD did not support 16 or15% layer diet CP (T4 and T5) but allowed to reduce CP (T3) by 1.0% (18.0 to 17.0%) to support production. BPD (2700/18.0/2.5) with BIS (2007) layer diet in T0 (2600/18.0/3.0) is the best combination for supporting BWG without affecting FC and improving EN, HDEP, FCDE, EFPR and PEI in layers.

Influence of the calcium and nutrient content of the prelay diet on egg production, egg quality, and tibiae mineralization of brown egg-laying hens from 16 to 63 wk of age

The influence of the Ca and nutrient content of the diet fed from 16 to 19 wk of age, on egg production, egg quality, and tibiae mineralization, was studied in brown egg-laying hens from 16 to 63 wk of age. The experimental design was completely randomized with 4 prelay diets organized as a 2×2 factorial with 2 levels of Ca (2.5 vs. 3.8%) and 2 standardized ileal digestible Lys (g/kg) to AMEn (Mcal/kg) ratios (DLys:ME; 2.84 vs. 3.13) as main effects. From 20 to 63 wk of age, all hens received a common diet with 2.75 Mcal AMEn/kg, 0.75% DLys, and 3.8% Ca. Each treatment was replicated 18 times and the experimental unit was a cage with 10 hens. Hen production and egg quality traits were measured by period (4 wk), feeding phase (prelay and lay), and cumulatively (16-63 wk of age) and tibiae mineralization was measured at 63 wk of age. During the prelay phase, an increase in Ca delayed egg production (P=0.065), reduced feed intake (P < 0.05), and increased BW gain (P < 0.01) and percentage of shell of the egg (P < 0.05). An increase in the DLys:ME ratio increased feed intake (P < 0.01) and reduced egg size (P < 0.01). Nutrient content of the prelay diets did not affect hen production during the lay phase, except egg weight that increased (P < 0.05) in hens previously fed the low DLys:ME ratio. Eggshell quality (weight, percentage, strength, and thickness) in this phase was better (P < 0.05) in hens previously fed 3.8% Ca. Cumulatively (16-63 wk of age), hens fed the high Ca prelay diets had better shell quality but tibiae mineralization was not affected. In conclusion, an increase in Ca content of the prelay diet from 2.5 to 3.8% improved shell quality for the entire egg cycle without showing any negative effect on hen production.

Effect of Different Nutrient Density Prelay Diets on Production Performance of White Leghorn Layers

Background: Transitional phase of 2-3 weeks (prelay) before onset of egg production is extremely important for efficient layer. This study evaluates different nutrient density prelay diets on the subsequent performance of White Leghorn layers. Methods: Total 180, 16-week-old White Leghorn pullets assigned to six-prelay feeding strategies (kcal ME per kg/%CP/%Ca) during 16-18 weeks. Treatments were T0 (BIS control-2500/16.0/1.0), T1 (2700/16.0/1.0), T2 (2700/16.0/2.0), T3 (2700/16.0/2.5), T4 (2700/18.0/2.0) and T5 (2700/18.0/2.5). Subsequently, pullets were fed with same layer diet (2600/18.0/3.0) during 19-40 weeks. Various growth and production parameters were recorded. Result: The 18% CP (T4 and T5), 2.0-2.5% Ca (T2 to T5) and 2700 kcal ME/kg (T1 to T5) in prelay diet significantly increased pullets daily metabolic energy (p less than 0.05), protein (p less than 0.05) and calcium (p less than 0.01) intake during 16-18 weeks than 2600 kcal ME/kg (T0), 16.0% CP (T0 to T3) and 1.0% Ca (T0). Prelay diet (T5) improved egg number, per cent egg production, feed efficiency, performance efficiency index and egg feed price ratio without affecting weight gain and feed consumption suggesting that prelay diet is a compromise between grower and layer diets.

Effect of Different Nutrient Density Prelay Diets on Egg Qualities of White Leghorn Layers

Background: Currently prelay nutrition has gained attention in layer industry. Consumer concern attracted researchers to study on different egg qualities. The study was aimed to investigate the impact of different nutrient density prelay diets on egg qualities. Methods: Total 180, 16-week-old White Leghorn pullets assigned to six-prelay feeding strategies (kcal ME per kg/%CP/%Ca) during 16-18 weeks. Treatments were T0 (BIS control-2500/16.0/1.0), T1 (2700/16.0/1.0), T2 (2700/16.0/2.0), T3 (2700/16.0/2.5), T4 (2700/18.0/2.0) and T5 (2700/18.0/2.5). Subsequently, pullets were fed with same layer diet (2600/18.0/3.0) during 19-40 weeks. Various egg quality parameters were recorded during 24-40 weeks of age. Result: Inclusion of 18.0% CP, 2700 kcal ME/kg significantly improved 40th week egg weight (p less than 0.05) and albumen index while reduced yolk weight (p less than 0.01). Prelay diet did not influence shape index and yolk index. The 18.0% prelay CP significantly (p less than 0.01) improved albumen weight and haugh unit. Inclusion of 2.0-2.5% prelay Ca significantly (p less than 0.01) improved shell weight and shell thickness than 1.0%. It is recommended to use 18.0% CP, 2700 kcal ME/kg and 2.5% Ca in prelay diet during 16-18 weeks along with BIS (2007) layer diet during 19-40 weeks age in White Leghorn Layers.

Dietary Energy and Protein Levels During the Prelay Period on Production Performance, Egg Quality, Expression of Genes in Hypothalamus-Pituitary-Ovary Axis, and Bone Parameters in Aged Laying Hens.

Nutrition during the pre-lay period takes effect on the production performance in the laying flock. This study evaluated the effects of dietary energy and protein levels in pre-lay diet on performance during the whole laying period and the egg quality, bone quality, and mRNA expression of hypothalamus-pituitary-gonadal (HPG) axis-related genes of hens at the end of the laying cycle. A total of 1,856 15-wk old Hy-Line brown pullets were randomly assigned to one of the four dietary treatments: using a 2 × 2 factorial arrangement with 2 energy levels (2,700 and 2,800 kcal/kg ME, respectively) and 2 protein levels (15 and 16.5% CP, respectively). Pullets were fed ad libitum from 15 to 20 wk and from 20 wk onward, fed with a similar laying diet till 72 wk of age. At 72 wk, the expression of genes in the hypothalamus, pituitary, ovarian, and follicles and bone quality was evaluated. At 72wk, there were no differences in production performance, BW, organ index, and ovarian parameters among the dietary treatments. High-CP diet increased the egg shape index and eggshell thickness (p < 0.05), but the eggshell breaking strength, Haugh unit, and albumen height did not differ among the treatments. Neither dietary energy nor protein level took an effect of bone quality. Low-energy diet increased the mRNA expression of gonadotropin-releasing hormone-1 (GnRH-1) in the hypothalamus (p < 0.05). The mRNA expression level of estrogen receptor-1 (ESR-1) in the hypothalamus and ovary was elevated by the 2,700 ME-15%CP diet (p < 0.05). The expression of cytochrome family 17 subfamily A polypeptide 1 (CYP17A1) in the large white follicle (LWF), small yellow follicles (SYF) and dominant follicle (DF) was decreased by the 2,800 kcal/kg diet (p < 0.05). These results indicate that the prelay diet had no influence on the production performance but had minimal effect on the eggshell characteristics and bone parameters. These results suggest that the energy and protein level of the prelay diet changes the expression of HPG axis-related genes of hens around the end of the laying cycle without changing the circulating sex hormone profile. The effect of prelay diet on the endocrinal adjustment at the end of the laying cycle needs to be investigated further.

Effects of a Rearing Dietary Protein Regimen on Productive Performance, Egg Quality, and Bone Quality of Laying Hens.

The pullet phase is an important stage in the development of laying hens when the development of organs, including reproductive organs and bones, is rapid. However, in recent years, few studies have focused on this crucial stage. The purpose of this study was to evaluate the effect of a dietary crude protein (CP) regimen during the rearing period (9-21 weeks (wks) of age) on pullet development and the subsequent performance, egg quality, and bone quality of Hy-Line Brown laying hens. A total of 256 pullets were randomly assigned to two treatments. Each treatment was replicated eight times with 16 pullets per replicate (n=8), which were fed ad libitum using either of the two CP regimens: (1) 14%-18% CP (fed with 14% and 18% CP from 9-17 wks and 18-21 wks, respectively); (2) 16% CP (fed with 16% CP from 9-21 wks of age). At 21 wks of age, eight birds per treatment were randomly selected to evaluate body composition and ovarian development. For quality analysis, eggs were collected at 28, 32, 36, and 70 wks. At 70 wks of age, eight hens per treatment were selected to evaluate bone quality. There were no treatment differences in pullet performance, body composition, and ovarian development at 21 wks. The dietary CP regimen during the rearing period (9-21 wks) did not influence laying performance during the laying period. There were no treatment differences in tibial and femoral quality at 70 wks. Egg quality results showed an inconsistent trend. It was concluded that the pullets fed with the low CP grower diet (14%) during the pullet period and a high CP pre-lay diet (18%) from 18-21 wks of age developed properly and had satisfactory laying performance. However, the rearing diet did not enhance bone quality.

Effects of pre-lay dietary calcium (2.5 vs. 4.0%) and pullet strain (Lohmann Brown vs. Selected Leghorn LSL-Lite) on calcium utilization and femur quality at 1st through to the 50th egg

To study the effects of pre-lay dietary Ca and strain on Ca utilization and femur quality at 1st through to 50th egg, 30 Lohmann Brown (LB) and 30 Lohmann Selected Leghorn-Lite (LSL) pullets (14 weeks of age, woa) reared under same management regimen were used. Six pullets/strain were necropsied for baseline femur samples and the rest (24 pullets/strain) placed in individual cages (65 × 30 × 45 cm3) and fed 1% Ca developer diet for 2 wk. At 16 woa, all pullets were weighed and allocated within strains to pre-lay diets (2.5vs. 4.0% Ca) effectively creating a 2 × 2 factorial arrangement. The pullets were offered pre-lay diets for 2 wk and switched to 4% Ca diet at 18 woa. The diets contained TiO2 to determine apparent retention (AR) of Ca. The age, BW, and feed intake (FI) at 1st, 25th, and 50th egg were recorded. Excreta samples were taken during pre-lay, at 1st and 25th egg and 4 hens per treatment were necropsied for femur samples at 1st, 25th, and 50th egg. There was no interaction (P > 0.05) between pre-lay Ca and strain on Ca intake, femur mineral density (FMD), mineral content (FMC), breaking strength (FBS), and ash (FA) content at 1st, 25th, and 50th egg. At 1st egg, pre-lay Ca interacted with strain on AR of Ca (P = 0.014) such that LB hens retained more Ca at 2.5vs. 4.0% Ca or LSL at 2.5% Ca. Pre-lay Ca had no effect (P > 0.05) on FMD, FMC, FBS, and FA at 1st, 25th, and 50th egg lay. Compared with LB hens, LSL hens had higher FMD (0.30vs. 0.19g/cm2; P = 0.010) and FA (51.9vs. 42.5%; P < 0.01) at 1st egg and FBS (259.4vs. 173.8N, P < 0.01) at 25th egg. In conclusion, except at 25th egg, pre-lay Ca and strain had independent effect on Ca utilization. Femur attributes to 1st egg suggested innate need for LSL birds to accumulate critical bone mass prior to first oviposition.

Effect of Diets with Various Calcium and Boron Levels in Prelaying Period on Growth, Bone Ash and Subsequent Performance and Shell Quality of Laying Hens

This experiment was conducted to determine the effects of diets with three different levels of calcium (% 0.8, 1.6, 3.2) and four different levels of boron (0, 75, 150, 300 mg kg-1) in prelaying period (14-20 weeks) on growth, bone ash and subsequent performance and egg shell quality of laying hens. A total 864 Super Nick pullets at 14 weeks of age were randomly allocated to twelve treatments arranged in a 3x4 factorial design with six replicates of 12 pullets each. Feed and water provided for ad-libitum access. The tibia samples were taken, three pullets and hens from every replicates at 20 and 42 weeks of age, respectively. Results of the present experiment showed that body weights and body weight gains were reduced in high prelay dietary Ca and B as the main factor. Feed intake of the pullets was not significantly influenced by the treatments. There were no detectable difference in feed intake, egg production, egg mass and feed conversion ratio (g, feed/ g, egg mass) and eggshell weight, but interactive effects of dietary Ca and B levels on eggshell thickness, egg specific gravity and shell breaking strength was significant. Shell thickness and breaking strength were significantly higher in hens fed pre-lay diet with 3.2 % Ca and no supplemental B than other treatments and egg specific gravity was significantly reduced by feeding 1.6 % Ca and 75 mg kg-1 B at 36 weeks of age. Bone ash (g or %) of hens at 20 and 42 weeks of age was not changed by Ca levels or interaction dietary Ca and B levels, but pullets receiving the 150 mg kg-1 B as the main factor had significantly higher in bone ash (g or %) values than other dietary B levels.

Transitional pullet feed and its significance at sexual maturity

Two biological experiments were carried out to find out the optimum energy, protein and calcium requirements in prelay pullet diets. Experiments involved different protein, energy and calcium levels during pre-lay period, two to three weeks before sexual maturity. It was revealed that a pre-lay diet with 2700 kcal/kg of energy, 18 per cent protein with 1.5 or 2 per cent calcium produced pullet at lower cost, had better body protein and fat and influenced bone status in terms of higher defatted dry tibial bone weight and longer and wider tibial bone. It could be concluded that pre-lay diet containing 2700 kcal/kg of dietary energy, 18 per cent C.P. and 2 per cent calcium is advisable for pullets before sexual maturity.

Efficacy of pre-lay diet

A biological study was carried out to review the Bureau of Indian Standards (BIS) recommendations for layer pullet feed. Commercial layer chicks were fed till 14 weeks of age as per BIS. At 15 weeks, pullets were randomly assigned to each of the five pre-lay feeding strategies, namely T1 (BIS control), T2 (16/2700), T3 (18/2700) (%CP/kcal ME/kg), T4 (same as T2 + lysine and methionine by 10% higher than BIS) and T5 (same as T4 with 2% oil). At 5% egg production, all groups were fed as per BIS. Pullets fed on high energy and protein pre-lay diets of 2700 kcal and 18% protein-advanced sexual maturity with good body composition. Pre-layers fed 2700/18 feed had the best hen day (85.44±1.52), hen-housed egg production (84.21±1.52), layed heavier eggs, had a higher egg mass output (47.14±0.95g), gave the best feed efficiency, had the lowest pullet production cost and high egg feed price ratio. It was concluded that pre-lay pullets have to be provided with 2700/18 kcal of metabolisable energy and protein level as against the BIS recommendation of 2500/16 dietary energy and protein level.

Distillers dried grains with solubles in pullet diets

SUMMARY A study was conducted to test the effects of dietary inclusion rate of distillers dried grains with solubles (DDGS) in Single Comb White Leghorn pullet diets. Four hundred twenty Hy-Line W-36 Single Comb White Leghorn pullet chicks were fed diets containing 0, 2.5, 5.0, 7.5, 10.0, or 12.5% DDGS from 1 d to 16 wk of age. Starter, grower, developer, and prelay diets were formulated to meet the bird requirements and were fed from 1 d to 6 wk, 7 to 9 wk, 10 to 15 wk, and 16 wk of age, respectively. Distillers dried grains with solubles was provided by Dakota Gold and contained 2,798 kcal/kg of ME and 26.7% CP. Average feed intake was similar among treatments regardless of DDGS levels, with a feed intake comparable with that in the Hy-Line W-36 manual. The overall pullet BW were also similar among dietary levels of DDGS. A time × treatment interaction approached significance (P = 0.07) for pullet BW; pullets fed 12.5% DDGS had greater BW than birds in the other dietary treatments at 14, 15, and 16 wk of age. Dietary treatments had no effect on mortality rate, resulting in only 0.07% total mortality. In summary, feeding up to 12.5% DDGS had no negative effect on growth performance and N and P retention levels. Nitrogen output increased at low levels of DDGS (2.5 and 5.0%), and P output decreased as DDGS levels increased. Feeding 12.5% DDGS had an economic benefit compared with feeding a corn-soybean meal diet.

Efficacy of pre-lay diets on pubertal growth spurt of commercial Leghorn pullets under humid tropical climate

The present study was carried out to review Bureau of Indian Standards recommendations for layer pullet feed under a hot and humid tropical climate. Commercial layer chicks were fed from 0 to 14 weeks of age as per BIS. At 15 weeks, pullets were randomly assigned to each of 5 pre-lay diets namely, T1 (BIS control), T2–16/2700, T3–18/2700 (%CP / kcal ME/kg); T4–same as T2+lysine and methionine by 10% higher than BIS, and T5 – same as T4 with 2 % oil. Pullets fed on high energy and protein pre-lay diets of 2700 kcal and 18% CP gave significantly better body weight at sexual maturity, pubertal growth spurt during transition period (2 to 3 weeks before sexual maturity), with better feed efficiency. It was concluded that, pre-lay diet is needed to accelerate pubertal growth spurt during transition period and to achieve target body weight at sexual maturity.

Efficacy of Saccharomyces cerevisiae fermentation product on intestinal health and productivity of coccidian-challenged laying hens

A 37-d laying hen experiment was performed to determine the effect of Diamond V XPC(LS) (XPC(LS), Diamond V Mills, Cedar Rapids, IA) during a subclinical Eimeria maxima infection on intestinal health and productivity. Two hundred and sixteen 18-wk-old Brown Nick laying hens were allocated to 24 litter pens based on a weight class system (9 hens/pen). The trial was carried out as a 2 × 2 factorial design with XPC(LS) and E. maxima challenge as main factors. Birds were fed a corn/wheat-based mash prelayer diet from wk 18 to 20 (10.9 MJ/kg of AME and 13.7% CP) and a standard phase I layer diet from wk 20 to 24 (11.7 MJ/kg of AME and 15.3% CP) that were supplemented with XPC(LS) at the rate of 0 or 0.75 g/kg. Hens were orally inoculated on d 23 (22 wk of age) with either 1 mL of saline (not infected) or 10,000 sporulated E. maxima oocysts/bird in 1 mL of saline (infected). Effects of XPC(LS) on intestinal health were determined by E. maxima lesion scoring. Results of E. maxima lesions were analyzed by Fisher exact, whereas severity of lesions and production parameters were analyzed by ANOVA. Supplementation of XPC(LS) significantly reduced severity of E. maxima lesions (P < 0.05) from 1.1 to 0.8 in challenged hens. An overall significant effect of XPC(LS) supplementation was demonstrated on d 34 by decreasing the severity of lesions from 0.3 to 0.1. The E. maxima challenge decreased (P < 0.05) production performance between 7 and 14 d postchallenge by lowering egg weight from 50 to 47 g/egg and laying rate from 84 to 70% and increasing feed per dozen eggs (P < 0.01) from 1.60 to 2.06 kg. Results indicate that Diamond V XPC(LS) supplementation reduced intestinal damage caused by an E. maxima infection in laying hens.

사료 내 Phytase 첨가가 산란계의 분뇨 배설량에 미치는 영향

National Institute of Animal ScienceABSTRACT This work was conducted to investigate the effects of phytase on N and P excretion of laying hens excreta. Three hundred sixty ISA Brown layers were selected to investigate excreta excretion for 65 weeks and to investigate the effect of phytase on total excretion and N and P excretion of layers from 55 weeks. The experimental diets were fed the starter (05 wk), grower (512 wk), developer (1216 wk), prelay diets (16 wkfirst egg), layer diets for starting period (first egg32 wk), middle (3245 wk), finishing diets (4555 wk, 55 wk). Thirty ISA Brown layers were selected to investigate the effect of phytase supple-mentation on total N and P excretion of layers at 55 weeks and assigned randomly to 3 treatments groups (10 birds/treatment) and phytase was added to basal diets at 300 and 600 FTU/kg. Average body weight, feed intake, water intake, and excreta excretion were 1,622, 105.7, 187.2 and 124.7 g/bird/day, respectively. Excreta of birds fed phytase were DM (33.2, 31.2, 30.5 g/day), N (0.46, 0.42, 0.40 g/day) and P (0.51, 0.49, 0.48 g/day) and reduced as dietary phytase increased, Finally, dietary phyase can reduce the N and P excretion, but the amount of excreta was not different depending from the phytase addition in layers. This work investigated the N and P excretion of laying hens excreta and were considered that dietary phytase can reduce the N and P excretion for short period.(Key words : phytase, layer, excreta excretion, N and P excretion)To whom correspondence should be addressed : kohb@korea.kr

Tracking the development of serum biochemical parameters in two laying hen strains – a comparative study

Abstract. A follow-up, comparative study was designed for the description of differences between two divergent laying hen strains, a Leghorn type and a medium heavy body (MHB) genotype (Hy-Line Brown), in chemical body composition and serum biochemical parameters determined at 3, 4, 6, 8, 10, 12, 14, 18, 20, 25, 30, 52 and 72 weeks of age; each time 5 birds of both genotypes were analysed and exterminated for body composition analysis. Resulting from the genotype-associated differences, the bodyweight of the populations differed from week 20 on. In the chemical body composition dry matter content was similar, while crude protein was higher on weeks 3, 8, 10, and after 18 weeks in the Leghorns. Crude fat content was higher in the brown birds (weeks 8, 10, 25, 30). Total serum protein and albumin showed slightly increasing trends, while serum creatinine concentration showed a downward trend in both genotypes, the MHB birds having higher values. Triglyceride concentration showed a drastic step-up at 17 weeks by changing to the pre-layer diet, coupled with marked between-genotype differences. This quick increase was matched by concentration drops in total and HDL cholesterol, the serum HDL cholesterol of Leghorns being always lower. Sodium concentration showed an increasing tendency with body DM content (R2=0.914, P&lt;0.001, n=115). The Leghorns tended to show minimally higher Ca concentrations. The γ-GT activity was always higher in MHB birds, indicating a less effective hepatic adaptation to the peak production. Applying discriminant analysis to classify the genotypes, 94.4% of the original grouped cases was correctly classified, using all variables.

Efeito dos teores de cálcio para poedeiras semipesadas durante a fase de pré-postura e no início da postura

O fornecimento de diferentes teores de cálcio para poedeiras semipesadas durante a fase de pré-postura e seus efeitos nas quatro semanas subseqüentes foram avaliados neste experimento. Foram utilizadas 288 aves da linhagem Isabrown com 16 semanas de idade, distribuídas em um delineamento inteiramente casualizado, com quatro tratamentos, oito repetições e nove aves por unidade experimental. As rações, à base de milho e farelo de soja, foram formuladas para atender às exigências nutricionais das aves, à exceção dos níveis de cálcio. O experimento teve duração de seis semanas, nas quais as aves receberam quatro rações pré-postura contendo diferentes teores de cálcio (0,6; 1,2; 1,8; e 2,4%) no período de 16 a 17 semanas de idade. Nas quatro semanas subseqüentes, foi fornecida uma ração de postura contendo 3,8% de cálcio para todas as aves. Não foi observado efeito dos tratamentos sobre o ganho de peso, a idade ao primeiro ovo e o teor de matéria mineral nas cascas dos primeiros ovos. Contudo, verificou-se efeito linear sobre a quantidade de cálcio depositado na casca. Nas quatro semanas subseqüentes, os diferentes teores de cálcio fornecidos na fase pré-postura não afetaram o consumo de ração, a produção de ovos, a conversão alimentar, os pesos dos ovos e da casca, a espessura da casca e a concentração de cálcio na casca, mas influenciaram linearmente o peso da casca em relação ao peso do ovo, o peso da casca por unidade de superfície de área e a quantidade de cinzas na casca. Os níveis nutricionais de cálcio nas rações pré-postura não afetaram a qualidade interna e externa dos ovos no início da postura. O nível nutricional de 0,6% de cálcio nas rações foi adequado para frangas semipesadas na fase pré-postura.

Responses of IsaBrown laying hens to a pre-layer diet containing additional calcium and to dietary protein and lysine concentrations during lay

IsaBrown pullets were obtained from a commercial breeder at 15 (Expt 1) and 16 (Expt 2) weeks of age and housed in either single-bird or multiple 5-bird cages in a high rise, windowless layer house in which temperatures were maintained below 30˚C by computerised control of fans and evaporative cooling pads. In Expt 1, they were fed either a grower diet or a pre-layer diet consisting of the grower diet containing additional calcium to 18 weeks of age and then maintained during lay to 56 weeks of age on diets containing either 160 or 180 g crude protein (CP)/kg. In Expt 2, they were fed the grower diet to 19 weeks of age and then 1 of 5 diets similar in all ingredients except that the lysine concentration varied between 7.35 and 8.95 g/kg in increments of 0.4 g/kg. The L-lysine HCl supplements were added in lieu of solka floc, an inert cellulose supplement. In Expt 1, mortality was low (2.25%), peak egg production was high (95–98%), and the mean rate of lay at 56 weeks of age was above 88%. The diet fed prior to lay had no significant effect on production during lay. Feed intake and egg production were similar for hens fed both dietary protein levels during lay, and egg weight and egg mass output were greater for hens fed the diet containing 180 g CP/kg. Hens in multiple-bird cages ate significantlyless feed for a significantly smaller daily egg mass output. In Expt 2, increasing the dietary lysine concentration significantly reduced feed intake and significantly increased lysine intake, egg shell breaking strength, and albumen height. Multiple-caged hens had a significantly lower hen-housed egg production as a result of a 7-fold increase in mortality compared with hens in single cages, due mainly to cannibalism. The daily lysine requirement formaximum egg production approximated 940 mg for hens in single cages and 975 mg for hens in multiple-bird cages.

Influence of Prelay Treatment and Dietary Protein Level on the Reproductive Performance of White Leghorn Hens

Two experiments were undertaken to study the influence of prelay diet treatment on subsequent laying performance. Feeding either a conventional laying or growing diet or diets containing essentially only wheat bran from 18 to 21 wk resulted in little grower diet carryover effect beyond 24 wk of age, although the wheat bran diets resulted in a marked drop in body weight of the pullets during the prelay treatment. Similar performance was noted for pullets in a second experiment in which prelay treatments consisted of feeding just corn or wheat bran from 18 to 20 wk of age. In interpreting the results of the present study, it is important to consider the fact that “mature pullet weights” were obtained before the prelay diet treatments were employed. Where prelay diet treatments have had significant effects on laying house performance, in most cases, immature or underweight pullets were involved.Feeding hens low-protein diets (13 versus 17%) from 20 to 44 wk of age resulted in similar egg production; however, egg weight and thus egg mass were slightly reduced with the lower protein diet. There was no laying by growing treatment interaction. The importance of good pullet weight at the start of the production cycle and the subsequent performance of such pullets fed low-protein diets is discussed.

Effect of a High-Protein Diet Fed Prior to the Onset of Lay on Performance of Broiler Breeder Pullets

The influence of protein level (154 versus 181 g/kg) in a prelayer diet fed from 134 to 181 days of age on the subsequent performance of hens was studied with two strains of broiler breeders.Birds given the prelayer diet of 181 g protein/kg showed higher egg production, 110 versus 101 eggs per bird, and a lower requirement for amount of feed per egg. The differences were noted mainly in the period 3 5 to 50 weeks of age. No differences were observed in age at 50% production, egg weight, incidence of cracked eggs, hatchability, or mortality.

Correction - The influence of calcium and phosphorus in prelayer diets and their interaction with sodium chloride and potassium sulfate in layer diets on egg production and shell quality in crossbred layers

In a 43x2 factorial experiment, 576 White Leghorn x Australorp pullets attaining 50% egg production at about 180 days of age were given from 22 to 26 weeks of age pre-layer diets with 10.4 or 25.8 g kg-1 calcium and 6.2 or 10.9 g kg-1 phosphorus. From 26 to 74 weeks of age these pullets were given layer diets with three levels (0, 1.5 and 7.0 g kg-1) of added sodium chloride and two levels (0 and 6.0 g kg-1) of added potassium sulfate. The calcium content of the pre-layer diet had no significant effect on feed intake, bodyweight gain or tibia-ash content between 22 and 26 weeks of age, or on egg production, egg weight, feed conversion efficiency and mortality in the subsequent laying phase. The higher level (25.8 g kg-1) of calcium improved (P&lt;0.05) the shell quality of the first eggs laid and prevented a decline in shell quality due to excess sodium chloride (7.0 g kg-1) in the layer diet. A phosphorus level of 10.9 g kg-1 of the pre-layer diet reduced (P&lt;0.05) feed intake, and in the subsequent laying phase both hen-housed egg production and efficiency of feed conversion were reduced (P&lt;0.05). The adverse effect on feed conversion efficiency was alleviated by adding potassium sulfate to the diet. The level of phosphorus in the pre-layer diet had no significant effect on tibia-ash content or egg shell quality. The dietary level of sodium chloride had no significant effect on egg weight, feed intake and bodyweight gain. The inclusion of sodium chloride at a level of 7.0 g kg-1 diet tended to depress rate of lay by 2.0% and during the first half of the laying cycle, increased mortality by 12.5% (P&lt;0.05) and reduced egg shell weight and thickness (P&lt;0.05) in birds given pre-layer diets with a low calcium content. A daily intake of 137 to 139 mg of sodium per bird was not adequate for maintenance of egg production and efficiency of feed conversion in crossbred layers. The sodium requirement of a crossbred layer given a diet containing meat and bone meal is about 160 mg/day. The adverse effects due to either a low intake of sodium or a high level of sodium chloride in the diet were alleviated by the inclusion of 6.0 g kg-1 potassium sulfate in the diet. The inclusion of potassium sulfate (6.0 g kg-1) in the layer diet increased rate of lay by 2.1% (P&lt;0.05).