J.W. van Riel

Field study on broilers’ first-week mortality

In the Dutch poultry meat production chain, first week mortality (FWM) of the chicks is an important measure to quality and is therefore highly related to the price of the chicks that the broiler farm has to pay to the hatchery. Therefore, next to the total number of broiler eggs produced per hen and hatchability, this figure is often used as a measure of efficiency in the breeder-hatchery-broiler production chain. In this study, factors that are related to chick mortality in the first week at broiler farms were investigated. Field data obtained from 2 commercial Dutch hatcheries, for which 482 broiler farms voluntarily recorded FWM of 16,365 flocks of broiler chicks over the years 2004, 2005, and 2006, were analyzed. These represented 79% of the total number of day-old chicks delivered to separate broiler farms. First week mortality was significantly related to breeder age, egg storage length at the hatchery, season, strain, feed company of the breeder farm, year, and hatchery. Furthermore, FWM differed significantly between chicks originating from eggs of different breeder flocks and which were kept for grow-out at different broiler farms.

Field Study on Broiler Eggs Hatchability

The aim of this research was to explore factors that are related with hatchability in the field. Data from 3 Dutch hatcheries for the years 2004, 2005, and 2006 were analyzed using a random regression model with the method of restricted maximum likelihood. In total, 24,234 batches of 724,750,444 eggs, originating from 511 breeder flocks, were included. Annually, 241,583,481 eggs were set on average, which is 37% of the total annual eggs set in the Netherlands. A significant difference in hatchability among eggs from different breeder flocks was found. Hatchability was significantly related with flock age, egg storage length, strain, feed company, season, year, as well as hatchery (P < 0.001). There was also significant interaction between flock age and age at first delivery, egg storage length at hatchery, strain, feed company, and season. Other 3-way interaction terms were also significant. The variation in hatchability was larger among the breeder farms than within breeder farms. The average estimated difference in hatchability among the hatcheries was 8%. The average estimated hatchability at 25 wk of age was 66%; it increased to 86% between 31 and 36 wk and decreased to 50% at 65 wk of age. On average, an extra day of storage until d 7 reduced hatchability by 0.2% and from d 7 to 14 by 0.5%. Eggs from older flocks were less sensitive to prolonged storage, whereas they were more sensitive to season. Hatchability was greater during late summer than during spring. The average estimated differences in hatchability among strains and feed companies of the breeder farms were 8 and 2%, respectively. Based on the relations found, optimization of hatchery results depends not only on good management at the hatchery but also on the hatching egg quality and therefore on the breeder farm management. It can be concluded that production data that are collected by the hatcheries can be used to adjust the management decisions at hatcheries as well as breeder farms.

Measuring foot-pad lesions in commercial broiler houses. Some aspects of methodology

For monitoring purposes there is a need for a protocol to measure foot-pad dermatitis (FPD) on-farm. Therefore, we studied the effect of number of birds sampled, number of locations sampled and sampling location in a broiler house on the accuracy of measurement, in order to construct a protocol that can be applied in practice. Samples were taken from eight commercial flocks (Ross 308) at up to ten locations with up to 25 birds sampled per location. Foot-pad lesions were scored in all birds for both feet using the Swedish scoring method. No significant differences in FPD score were found between the first five birds and all birds sampled at a particular location. Although locations near the walls did not differ in FPD score from locations in the central area of a house, the severity of foot-pad lesions was unevenly distributed over the house. A model was constructed showing the inaccuracy related to the number of locations sampled in the house and the number of birds sampled per location. The model shows that in situations with at least five locations differences in inaccuracy are relatively small when a total of 100 birds or more is sampled. Inaccuracy is largest in a flock with variation in foot-pad scores, as compared to flocks with little variation. The results of this experiment can be used to determine the optimal sample size in a commercial broiler house.

Effect of Bedding Material on Dust and Ammonia Emission from Broiler Houses

The objective of this study was to determine the effects of different bedding materials on fine dust (PM10 and PM2.5) and ammonia emissions from broiler houses. The effects on broiler performance and footpad lesions were also studied. The study was carried out in a mechanically ventilated broiler house with eight identical rooms, each accommodating 2260 broilers; it compromised two production cycles (rounds) of 35 days. The broilers were raised on four bedding materials: white wood shavings, chopped wheat straw, ground rapeseed straw, and silage maize. PM10, PM2.5, and ammonia concentrations and ventilation rates were measured. Production results and the incidence of footpad lesions were assessed. The results showed that compared with wood shavings, silage maize had 19% lower PM2.5 emission (p < 0.05). The PM2.5 emissions of silage maize were not different from those of wheat straw and rapeseed straw. Type of bedding had no effect on PM10 emission. PM2.5 mass was on average 4.8% of PM10 mass and increased with the age of the birds (p < 0.001). Ammonia emission from silage maize was 36% lower than from wood shavings, 47% less than from wheat straw, and 34% less than from rapeseed straw. Bedding material had no effect on broiler performance or on footpad lesions. It was concluded that silage maize can be a good alternative bedding to wood shavings and wheat straw in broiler houses.