The Quest for Welfare-Friendly Feeding of Broiler Breeders: Effects of Daily vs. 5:2 Feed Restriction Schedules

Abstract

Restricted feeding of broiler breeders is required for improved long-term health and welfare. Because feeding frustration and hunger are major welfare concerns during rearing, many suggestions have been made to decrease the negative feelings of hunger while maintaining suitable growth rates and reproductive health. Non-daily ("skip-a-day") feeding schedules are commonly used around the world to increase portion sizes at meal times while restricting intake but these practices are prohibited in many countries due to welfare concerns on fasting days. We compared birds raised on a non-daily feeding schedule (2 non-consecutive fasting days per week, 5:2), previously suggested as a welfare-friendlier non-daily alternative, to birds raised on daily feed restriction. We found signs of increased physiological stress levels in 5:2 birds, including elevated heterophil to lymphocyte ratios (1.00 for 5:2 vs. 0.75 for daily fed at 12 weeks of age), increased adiposity (0.21% lean body weight [LBW] for 5:2 vs. 0.13% LBW for daily fed), and reduced muscle growth (pectoral muscle 5.94% LBW for 5:2 vs. 6.52% LBW for daily fed). At the same time, 5:2 birds showed signs of lower anxiety before feeding times (activity was reduced from 10.30 in daily fed to 4.85) which may be a result of the lower feed competition associated with larger portion sizes. Although we found no difference in latency to first head movement in tonic immobility between the treatments (136.5 s on average for both groups), 5:2 birds generally showed more interest in a novel object in the home pen which indicated increased risk taking and reduced fear while fasting. The 5:2 birds in this study showed no signs of learning the feeding schedule, and this unpredictability may also increase stress. Taken together, the effects of 5:2 vs. daily feed restriction on the welfare of broiler breeder pullets remain inconclusive and differ between feeding and fasting days. In addition to reducing stress by minimizing the number of fasting days, we suggest that a shift to more predictable schedules may help improve the welfare of broiler breeder pullets.

Intermittent fasting induces chronic changes in the hepatic gene expression of Red Junglefowl (Gallus gallus)

“…Birds fed according to the CR and IF feeding regimens showed similar growth rates, although IF-fed birds had a consistently higher feed intake as previously reported (13). It is well known that the liver is central to the primary metabolic response to dietary changes in chickens (14), and shows large fluctuations in mass, glycogen content and lipid content under IF conditions in both RJF (13) and broiler breeders (10,15). Concomitant with these overt physiological effects are large effects on hepatic transcription.…”

“…The expression of these three inflammation-associated genes could indicate either a reduced need or a reduced capacity for inflammatory responses in IF-fed birds. At this point we cannot say which of these two explanations is more likely, but it is worth noting that IF leads to a modest increase in heterophil-tolymphocyte ratios (heterophils are the avian equivalent of neutrophils in mammals) which does suggest an immune activation under these conditions (10).…”

Intermittent fasting in chickens : Physiological mechanisms and welfare implications for broiler breeders

“…It has been reported that broiler breeders fed every other day, and thus given twice the amount of feed, take 2.5 times as long to finish their meals which would support the idea of reduced feed competition (Bennett and Leeson, 1989). Lower numbers of feather fault bars (Arrazola et al, 2019a) and reduced anticipatory behavior before feeding time (Lindholm et al, 2018) reported in IF-fed breeders are also suggestive of reduced competition stress in these animals. While these regimens have sometimes been criticized for imposing high stress levels on fasting days (Renema and Robinson, 2004), others have concluded that IF regimens do not increase overall stress levels compared to daily feeding as assessed by HLRs and behavioral observations (Skinner-Noble and Teeter, 2009).…”

“…AgRP also appears to be involved in driving the increase in locomotory behaviors that is typical of feed-restricted animals in anticipation of food (Thomas and Xue, 2018). This behavior is independent of the circadian rhythm control in the suprachiasmatic nucleus (Thomas and Xue, 2018) and is also well documented in chickens (D'Eath et al, 2009;Kostal et al, 1992;Lindholm et al, 2018;Savory and Lariviere, 2000). The appetitive effects of AgRP are further supported by studies showing that presentation of food, especially if it is palatable, to a calorie-deficient rodent reduces AgRP and increases POMC expression within seconds.…”

Conditioned place avoidance using encapsulated calcium propionate as an appetite suppressant for broiler breeders Conditioned place avoidance and calcium propionate

“…https://doi.org/10.1101/441220 doi: bioRxiv preprint Buckley and colleagues [40], pullets under commercial feed restriction had shorter latencies than pullets fed at 80% of ad libitum feed intake in a T-maze choice test. Previous research with broiler breeders also noted that fearfulness linearly decreased as feed restriction increased [14,15] and during off-feed days under non-daily feed restriction [43]. For this reason, light broiler breeders under feed restriction conditions display high arousal as suggested by short latency and low fearfulness in behavioural tests [40][41][42], probably being less consistent in short-term choices due to previous experiences and current feeding motivation.…”