Factors Associated with Cumulative First-Week Mortality in Broiler Chicks

Abstract

First-week mortality is an important performance index as well as an important welfare indicator. The aim of the present study was to identify internal (individual-dependent) and external (management or environmental) factors that could influence the cumulative first-week mortality of broilers. To carry out this study, field data obtained from a hatchery company were used, in which 2267 flocks of broiler chicks (from 2015 to 2018), were analyzed. A generalized linear mixed model was used to analyze the data. Farm ID and house by farm were incorporated as random effects. The Odds Ratio was estimated for each factor, determining the effect of each explanatory variable. First-week mortality was significantly related to breeder age (p < 0.0001), chick gender (p < 0.0001) and breed (p < 0.0001) as internal factors, and type of broiler house (p = 0.0129), presence or absence of drip cup (p < 0.0001), egg storage (p < 0.0001), study year (p < 0.0001) and season (p < 0.0001) as external factors. Therefore, these factors should be considered in the decision making of poultry breeding companies, in order to reduce possible welfare problems and increase productive performance.

Risk factors for poor health and performance in European broiler production systems

“…This result is confirmed by two other studies, who found a higher first week mortality in broiler houses with negative pressure ventilation compared to naturally ventilated houses [8,10]. However, a more recent Spanish study found no influence of ventilation on first week mortality [9]. These three studies are all studies conducted within one country (Norway, Taiwan and Spain resp.…”

“…However, there are only few epidemiological studies taking a more integrated approach with multivariable modeling in order to identify and weigh the different risk factors threatening performance and health of broilers in field conditions without focusing on only one or a few specific preselected diseases or clinical features. Flock size, stocking density, use of paper underlay for feeding during the 1st week for example have been identified as risk or protective factors for first week mortality [8,9]. The same study also identified that age of the broiler house, heating system and control system for the air intake could be associated with broiler mortality after seven days.…”

Genotype and breeder flock age impact on broiler performance in suboptimal conditions

“…This is also indicated by Leeson and Sumers (2005), who reared broilers from parents aged 28, 38, 48 and 58 weeks in the same facility and standard conditions and noticed that with the age of the parents, the final and broiler carcass weights increased, especially in females. It should be noted that in our research, broilers from young and from middle-aged, the so-called prime breeders (Yerpes et al, 2020), were not used, but from parents in the final phase of the first cycle of laying (52 weeks) and broilers from parents in the second cycle of laying after moulting (79 th week), i.e. relatively old and "very" old parents regarding production life, which, judging by the available literature, was rarely compared.…”

“…El-Tahawy et al (2017) also find no significant difference in mortality between these two hybrids on farms in general (about 2%), but indicate significantly higher mortality on small farms (up to 10,000 broilers), where Cobb 500 has a mortality of 6.15% and Ross 308 4.06%, which is explained by the relatively poorer farm conditions. On the other hand, analysing the factors that influenced the cumulative mortality in the first week of broiler fattening (including culled birds) in 2267 flocks in 253 fattening farms on 104 farms of one poultry company in Spain from 2015-2018, Yerpes et al (2020) conclude that, among others, the genotype (breed) used and the age of the parents have a significant impact. The authors state that during the first week, chickens of Ross genotype died more (1.85%) than the Cobb genotype (1.72%), without specifying specific hybrids, and that broilers originating from older parents had higher mortality.…”

5-Hydroxytryptophan Suppresses the Abdominal Fat Deposit and Is Beneficial to the Intestinal Immune Function in Broilers

“…The experiment started from the Day 8 to let all the broiler chicks adapt the rearing environment (Yassin et al, 2009;Yerpes et al, 2020). All the experimental chicks were fed with a cornsoybean basal diet (21% crude protein) until 7 days of age.…”