Biology subjects

Widowski, T. M.

Publications and source records attributed to Widowski, T. M..

3 recordsLinked to original sources

bioRxiv2021

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

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 strains specific growth rate.

animal behavior and cognition↗

bioRxiv2020

In Pursuit of a Better Broiler: Growth, Efficiency and Mortality of 16 Strains of Broiler Chickens

To meet the growing consumer demand for chicken meat, the poultry industry has selected broiler chickens for increasing efficiency and breast yield. While this high productivity means affordable and consistent product, it has come at a cost to broiler welfare. There has been increasing advocacy and consumer pressure on primary breeders, producers, processors and retailers to improve the welfare of the billions of chickens processed annually. Several small-scale studies have reported better welfare outcomes for slower growing strains compared to fast growing, conventional strains. However, these studies often housed birds with range access or used strains with vastly different growth rates. Additionally, there may be traits other than growth, such as body conformation, that influence welfare. As the global poultry industries consider the implications of using slower growing strains, there was a need for a comprehensive, multidisciplinary examination of broiler chickens with a wide range of genotypes differing in growth rate and other phenotypic traits. To meet this need, our team designed a study to benchmark data on conventional and slower growing strains of broiler chickens reared in standardized laboratory conditions. Over a two-year period, we studied 7,528 broilers from 16 different genetic strains. In this paper, we compare the growth, efficiency and mortality of broilers to one of two target weights (TW): 2.1 kg (TW1) and 3.2 kg (TW2). We categorized strains by their growth rate to TW2 as conventional (CONV), fastest slow strains (FAST), moderate slow strains (MOD) and slowest slow strains (SLOW). When incubated, hatched, housed, managed and fed the same, the categories of strains differed in body weights, growth rates, feed intake and feed efficiency. At 48 days of age, strains in the CONV category were 835-1264 g heavier than strains in the other categories. By TW2, differences in body weights and feed intake resulted in a 22 to 43-point difference in feed conversion ratios. Categories of strains did not differ in their overall mortality rates.

physiology↗

bioRxiv2020

Acute stressors experienced by layer breeders do not affect measures of stress and fear in their offspring

Stressors experienced by layer breeders during egg production can lead to changes in the egg hormone content, potentially impacting their offspring, the commercial layers. Genetic differences might also affect the offsprings susceptibility to maternal experiences. In this study, we tested if maternal stress affects measures of stress and fear in five strains of layer breeders: commercial brown 1 & 2, commercial white 1 & 2 and a pure line White Leghorn. Each strain was equally separated into two groups: "Maternal Stress" (MS), where hens were subjected to a series of 8 consecutive days of acute psychological stressors, and "Control," which received routine husbandry. Additional eggs from Control were injected either with corticosterone diluted in a vehicle solution ("CORT") or just "Vehicle." Stress- and fear-responses of the offspring were measured in a plasma corticosterone test and a combined human approach and novel object test. Both MS and CORT treatments failed to affect the measured endpoints in the offspring, but significant strain differences were found. The offspring of the white strains showed a higher physiological response compared to brown strains, but the White 2 offspring was consistently the least fearful strain in the behaviour tests. Our study found that the acute psychological stressors experienced by layer breeders did not affect the parameters tested in their offspring and that corticosterone does not seem to be the primary mediator of maternal stress in laying hens. This is highly important, as in poultry production, layer breeders are often subjected to short-term stressors. In addition, we successfully dissociated the physiological and behavioural parameters of stress response in laying hens, showing that increased concentrations of plasma corticosterone in response to stress is not directly associated with high levels of fear.

animal behavior and cognition↗