Interventions to reduce the bacterial load in recycled broiler litter.

Two experiments were undertaken to evaluate the bacterial load in recycled litter between broiler flocks following addition of quicklime (T1), windrowing (T2), shallow fermentation (T3), and control (no intervention, T4). The first experiment was developed in field conditions in which the broiler houses were accompanied by 6 consecutive flocks and the effect of the treatments was assessed on enterobacteria and aerobic mesophiles. The second experiment was conducted in an experimental broiler house with recycled litter for assessment of Salmonella Enteritidis phage type 4 (SE PT4). In the field study, T3 presented the best results in reducing enterobacteria in broiler litter in relation to the other treatments, with the highest reduction occurring in the first 3 flocks, tending to stabilization from the fourth flock onward for all the treatments assessed. From the third to sixth flocks, enterobacteria level at the end of the treatments (d 12) was lower than the average in the fresh litter, except in T4. All treatments reduced aerobic mesophiles throughout the flocks, where T2 showed the highest reduction. The percentage of dry matter in the broiler litter diminished in T4 and increased in T3 over the course of the flocks. In the second experiment, the drop in the SE PT4 level in the broiler litter first occurred in T2 and T3. However, all the treatments except for T4 eliminated SE PT4 within 12 d. The temperature of the broiler litter in T2 was higher in relation to the other treatments. The results show that litter treatment prior to reutilization by the successive broiler flock is required to reduce the level of residual bacteria. The fermentative treatments (T2 and T3) were found to be superior to the others in terms of reducing the bacterial load, with shallow fermentation standing out with the highest reduction of enterobacteria and equivalent SE PT4 elimination when compared to windrowing.

Comparison of the effect of different methods of molt: production and welfare evaluation.

The purpose of this study was to evaluate alternative molting protocols assessing hen welfare and performance during and after molt. Hyline W-36 pullets were housed at 15 wk of age, and their egg production was obtained during this first cycle. When birds were 80 wk, the following molting treatments were applied: a conventional molt consisting of 10 d of fasting followed by cracked corn for 8 d and a pullet developer diet for 10 d; and 4 alternative molting programs: a soy hulls-based diet (12% CP, 1,455 kcal/kg of ME, and 1.38% Ca) offered for 14 d followed by cracked corn for 4 d and a pullet developer diet for 10 d; and the other 3 molt regimens consisted of feeding soy hulls for 4, 8, or 12 d followed by 10, 6, or 2 d, respectively, of a soy hulls-based diet and 4 d of cracked corn plus 10 d of a pullet developer diet. A nonmolted group of birds was fed a laying hen diet during the experimental period. Hen-day egg number was recorded daily for 56 wk (through 80-136 wk of age). The nonmolted hens showed lower hen-day production and fewer intact eggs and a higher number of cracked and shell-less eggs compared with those of the molted hens (P < 0.0001). A significant treatment by age effect (P < 0.0001) was observed for the variables of high-density lipoproteins and triglycerides. Control hens showed the lowest high-density lipoprotein concentration and the highest triglyceride levels at 84 wk of age when compared with all treatments. The lack of difference in heterophil-to-lymphocyte ratio during molt suggests little influence of molting protocols on this variable. Regardless of the treatments, molting was deleterious to bone quality. A high mobilization of Ca through bone resorption for eggshell formation could explain the results obtained. Behavioral patterns coincided with a decline in frustration activities and an increase in alertness as molt proceeded until 83 wk of age. Alternative molting diets consisting of soybean hulls were successful in providing acceptable postmolt egg production performance.

Comparison of restricted maximum likelihood and method R for estimating heritability and predicting breeding value under selection.

Method R and Restricted Maximum Likelihood (REML) were compared for estimating heritability (h2) and subsequent prediction of breeding values (a) with data subject to selection. A single-trait animal model was used to generate the data and to predict breeding values. The data originated from 10 sires and 100 dams and simulation progressed for 10 overlapping generations. In simulating the data, genetic evaluation used the underlying parameter values and sires and dams were chosen by truncation selection for greatest predicted breeding values. Four alternative pedigree structures were evaluated: complete pedigree information, 50% of phenotypes with sire identities missing, 50% of phenotypes with dam identities missing, and 50% of phenotypes with sire and dams identities missing. Under selection and with complete pedigree data, Method R was a slightly less consistent estimator of h2 than REML. Estimates of h2 by both methods were biased downward when there was selection and loss of pedigree information and were unbiased when no selection was practiced. The empirical mean square error (EMSE) of Method R was several times larger than the EMSE of REML. In a subsequent analysis, different combinations of generations selected and generations sampled were simulated in an effort to disentangle the effects of both factors on Method R estimates of h2. It was observed that Method R overestimated h2 when both the sampling that is intrinsic in the method and the selection occurred in generations 6 to 10. In a final experiment, BLUP(a) were predicted with h2 estimated by either Method R or REML. Subsequently, five more generations of selection were practiced, and the mean square error of prediction (MSEP) of BLUP(a) was calculated with estimated h2 by either method, or the true value of the parameter. The MSEP of empirical BLUP(a) using Method R was greater than the MSEP of empirical BLUP(a) using REML. The latter statistic was closer to prediction error variance of BLUP(a) than the MSEP of empirical BLUP(a) using Method R, indicating that empirical BLUP(a) calculated using REML produced accurate predictions of breeding values under selection. In conclusion, the variability of h2 estimates calculated with Method R was greater than the variability of h2 estimates calculated with REML, with or without selection. Also, the MSEP of EBLUP(a) calculated using estimates of h2 by Method R was larger than MSEP of EBLUP(a) calculated with REML estimates of h2.

Coccidiose e desempenho em frangos com anticoccidianos na raçäo a partir de diferentes idades / Coccidiosis and perfomance in broilers with anticoccidial medicated feed starting at different ages

Estudou-se o efeito da idade das aves, da reutilizaçäo da cama vegetal e de programas anticoccidianos na coccidiose e desempenho de frangos. Utilizaram-se quatro lotes de 24 pintos cada (um dia de idade) submetidos a quatro tratamentos (T): T1 - aves näo tratadas com anticoccidiano, T2 - aves medicadas com anticoccidiano a partir do 14º dia de vida, T3 - aves medicadas com anticoccidiano a partir do sétimo dia de vida, T4 - aves medicadas com anticoccidiano a partir do primeiro dia de vida. As contagens de oocistos aumentaram com a reutilizaçäo da cama, no terceiro lote. T1 (sem anticoccidiano) e T4 (anticoccidiano desde o primeiro dia) apresentaram as maiores contagens. Os escores por Eimeria acervulina aumentaram no terceiro lote e baixaram no quarto lote. Os escores por E. maxima aumentaram no segundo lote, e deste para o terceiro e quarto lotes. Os escores por E. tenella aumentaram no terceiro e quarto lotes. Com desafio alto, como ocorrido no terceiro lote, as medicaçöes anticoccidianas a partir do primeiro, sétimo e 14º dias resultaram em desempenhos semelhantes. Com desafios baixos ou moderados, como ocorridos nos lotes 1, 2 e 4, a medicaçäo a partir do 14º dia resultou em melhores desempenhos. Isso sugere que, em condiçöes de baixo desafio, como em frangos criados em cama de primeiro uso e em granjas com aves de uma única idade, a medicaçäo anticoccidiana a partir de 14º pode ser vantajosa em relaçäo aos programas de medicaçäo a partir do primeiro dia

Efeito da idade das aves e da reutilizaçäo e manejo da cama do aviário sobre a coccidiose em frangos de corte / Effect of bird age and reutilization and management of litter on broilers coccidiosis

Estudou-se o efeito da idade dos frangos, reutilizaçäo da cama do aviário e do seu manejo sobre a coccidiose em frangos de corte, num experimento em blocos casualizados, com cinco tratamentos e quatro repetiçöes por tratamento. Criaram-se quatro lotes consecutivos de frangos sobre a mesma cama de aviário submetida aos tratamentos (T). As contagens de oocistos aumentaram (P<0,05) a partir dos 28 dias de idade e gradualmente do lote dois ao lote quatro. No lote três, as contagens do T1 (cama virada três vezes no vazio sanitário) foram maiores (P<0,05) que as do T2 (cama amontoada por seis dias) e do T4 (amontoada e coberta com lona por seis dias); enquanto as do T3 (cama amontoada por 12 dias) e do T5 (amontoada e coberta por 12 dias) tiveram valores intermediários. Os escores por E. acervulina e E. tenella aumentaram (P<0,05) aos 35 e 42 dias. As lesöes por E. acervulina aumentaram (P<0,05) no lote três, e deste para o lote quatro. Os escores por E. tenella aumentaram no lote três. O ganho de peso aumentou (P<0,05) do lote um para os lotes dois e três, e destes para o lote quatro. Conversäo e margem bruta pioraram (P<0,05) no lote três, e voltaram a melhorar no lote quatro. A viabilidade piorou (P<0,05) no lote quatro. Nesse lote, as menores viabilidades ocorreram no T3 e T4