In pursuit of a better broiler: A comparison of the inactivity, behavior, and enrichment use of fast- and slower-growing broiler chickens

Abstract

Selection for rapid growth has produced heavier, more efficient broiler chickens, but has also introduced health and welfare issues, which may cause or be caused by inactivity. Rapid growth may also limit the performance of motivated behaviors, whereas the provision of enrichment may increase these behaviors and general activity. This study aimed to evaluate the inactivity, behavior, and enrichment use of 2 fast- (CONV) and 12 slower-growing broiler strains [categorized as fastest (FAST), moderate (MOD) and slowest slow (SLOW), based on their growth rates]. To evaluate inactivity, one male and one female from 153 pens were outfitted with omni-directional accelerometers from day 21 until processing (14-24 birds/strain from 8-12 pens/strain). Additionally, to supplement inactivity data, five-minute continuous behavioral observations of four focal birds per pen (2 males, 2 females) were conducted on days 26, 42, and 56 (72-148 observations of 8-12 pens/strain) to quantify the duration and frequency of various behaviors; at the same time, 5-11 instantaneous scan samples were also performed for pen-based enrichment use. Inactivity peaked at 78-80% of the day for all strains; however, those with slower growth rates reached these levels at older ages. Compared to slower-growing strains at the same age, faster-growing strains were more inactive, spent more time sitting and feeding, spent less time standing and walking, and used enrichments less; these differences mostly occurred at younger ages. Generally, at the same age, strains with similar growth rates (within the same category) behaved similarly, with only a few exceptions. Results suggest that not all strains identified as 'slow-growing' broilers behave differently from fast-growing broilers, nor do they all behave similarly to each other. As such, results suggest that improved broiler welfare, particularly with respect to reduced inactivity, the performance of a wider range of normal, motivated behaviors, and/or increased enrichment use, is related to the broiler strain's specific growth rate.

Welfare of broilers on farm

“…The frequency for exploratory and foraging behaviour might be influenced by genetics and husbandry systems (Yan et al., 2021), part of the animal's personality (Garnham and Løvlie, 2018) and range use (Ferreira et al., 2021). In addition, environmental enrichment including litter substrate (Monckton et al., 2020a) and other objects, higher space allowance (Bach et al., 2019) and (elevated) structures (Dawson et al., 2021) will promote exploration and foraging behaviour (Riber et al., 2018). Active exploratory and foraging behaviour in turn supports the locomotor and health status of the broilers.…”

“…The connection between locomotion and the hybrid of the animals is undisputed. Generally, slower growing broiler hybrids (hybrids with a growth rate of less than 50 g/day (Dixon, 2020; Dawson et al., 2021)) are less susceptible to develop locomotor problems as compared to fast growing hybrids (Dixon, 2020; Rayner et al., 2020). The mobility of broilers has a large impact on welfare.…”

“…For this EKE, walking is described as a slow forward movement, breast above the floor, using legs without performing any other activity (Ipema et al., 2020; Abeyesinghe et al., 2021). This does not include other types of locomotion such as running, wing‐assisted running or play fighting (Dawson et al., 2021).…”

Enhancing their quality of life: environmental enrichment for poultry

“…Among the factors not directly related to the enrichment are genetics, stocking density, and light intensity. Genetics play a major role in the activity level exhibited by broilers, where for example, fast growth rates may hamper the use of enrichments, but variation may also exist within genotypes of similar growth potential ( Almeida et al, 2012 ; Dawson et al, 2021 ). De Jong et al (2021) showed that although the fast-growing genotype used the enrichment less than the slower-growing genotype, the positive impact on overall activity level was similar for both genotypes.…”

Effects of Age on Behavioral-based Welfare Indicators of Slow Growing Broiler Raised in Experimental and Commercial Conditions

“…Birim metrekare alanda barındırma yoğunluğu hayvan refahı ile ilgili en önemli konulardan birisi olup (13,23), aynı barındırma yoğunluğu ölçüsünün deneysel ve ticari koşullardaki etkisi yavaş ve hızlı gelişen piliçlerde farklı olabilmektedir (24). Yavaş gelişen etlik piliçlerde normal ve korku davranışlarının hızlı gelişenlere göre farklı olduğu bilinmektedir (5,6,25). Ancak deneysel koşullarda yapılan çalışmalar genelde etrafı sınırlı daha dar alanlarda yapılmaktadır ve bu hayvanların yürüme, koşma gibi uzun bir alanda hareket edebileceği davranışları sınırlandırmaktadır.…”