Influence of a period of ‘freeze-feeding’ on behaviour of growing layer pullets

Dietary zinc supplementation and the performance and behaviour of caged laying hens

There is considerable behavioural evidence demonstrating stress reactions in birds. Behaviour of birds can affect their performance parameters. Also, nutritional factors may affect the behaviour of laying hens. Dietary deficiencies, such as minerals can increase feather-pecking behaviour and cannibalism. In the present study, we evaluate the effect of dietary zinc (Zn) on performance and behaviour of laying hens with four treatments (40, 70, 100, 130 mg Zn/kg of diet) with 96 Hy-Line W-36 leghorn hens for 10 weeks. The results showed that egg production for hens receiving 130 mg Zn/kg of diet was significantly higher than for those receiving 40 and 70 mg Zn/kg of diet (P < 0.05). Those hens receiving 130 mg Zn/kg of diet had lower feed consumption compared with those that had other treatments (P < 0.05). Dietary inclusion of Zn caused an improvement to feed conversion ratio (P < 0.05). There was a treatment × time interaction on feeding behaviour that hens received 130 mg Zn/kg of diet spent significantly less time at the feeder than the other treatments. Hens receiving 130 mg Zn/kg of diet spent significantly less time drinking than the hens that received 40 and 70 mg Zn/kg of diet. Also, those that received 130 mg Zn/kg of diet did more non-nutritive pecking and preening than the hens that received 40 and 70 mg Zn/kg of diet. High levels of Zn decreased the aggressive behaviour of hens compared with those that received 40 mg Zn/kg of diet (P < 0.05). It can be concluded that Zn can improve laying performance, and can decrease aggressive behaviour.

Influence of degree of food restriction, age and time of day on behaviour of broiler breeder chickens

Six groups of 25 growing female broiler breeder chickens in pens were fed either on a commercial restricted ration (R), twice that amount (2R), or ad libitum (AL). R and 2R birds were fed daily at 09.00 h and ate all their food in < 15 min. Behaviour was observed systematically at three times of day (once before and twice after feeding time) at 6,9,12, 15 and 18 weeks of age. In general, restricted-fed (R and 2R) birds were much more active than AL birds. There were significant (P < 0.05) effects of feeding treatment on all activities recorded except preening and pecking at the empty feeder (R and 2R birds only); age affected drinking, preening, walking, standing and sitting; and time of day affected all activities except feeding (AL birds only). Activities that appeared to reflect feeding motivational state closest were walking before feeding time, and drinking, pecking floor litter and sitting after feeding time. AL birds (only) panted for about a third of the time at moderate ambient temperatures, and changes in their behaviour with age were thermoregulatory. It is proposed that activities of restricted-fed animals that are dominant after feeding time may be substitutable and have common causation and consequences. Distinction between stereotyped and non-stereotyped behaviour in this context may therefore be misleading.

Behavioral responses of laying hens to different alfalfa-layer ration combinations fed during molting

Induced molting by feed withdrawal has been a common practice in the commercial layer industry and usually involves the removal of feed for a period of up to 14 d. However, this is a practice that is believed to adversely influence the welfare of the hens and there is a need to examine behavioral responses to alternative molt regimens. The behavioral patterns of hens on 90% alfalfa:10% layer ration, 80% alfalfa:20% layer ration, and 70% alfalfa:30% layer ration molt diets were compared with feed withdrawal (FW) hens, and fully fed (FF) hens. The White Leghorn laying hens were approximately 54 wk old and were placed in 3 identical climate-controlled rooms. The hens were individually housed in 2-tier wire battery cages and provided treatment rations and water ad libitum. Nonnutritive pecking, walking, drinking, feeder activity, preening, aggression, and head movement were quantified during two 10-min periods each day for 6 hens from each treatment. Over the 9-d treatment period, hens in the FW, 70% alfalfa:30% layer ration, and 80% alfalfa:20% layer ration groups spent significantly more time walking than hens in the 90% alfalfa:10% layer ration group. The FF and 70% alfalfa:30% layer ration hens spent half as much time preening, whereas the FW hens displayed nearly twice as much nonnutritive pecking when compared with other treatments. Most differences in head movements occurred at the beginning of the molt period, whereas during the last half of molt, alfalfa-fed hens exhibited feeder activity similar to FF hens, and all were significantly higher than that of FW hens. After some initial adjustment by the hens, consumption of alfalfa molt diets appeared to reduce nonnutritive pecking behavior, which is characteristically associated with FW hens.

Behavior of laying hens on alfalfa crumble molt diets

Several dietary alternatives to feed withdrawal have been proposed to induce a molt in laying hens. This study compared the behavior of laying hens on an alfalfa crumble diet (ALC) to hens that were either on a conventional layer diet (FF) or hens that had feed withdrawn (FW) during a 9-d trial. Each treatment consisted of 24 hens (3 hens per battery cage), and treatment began after a 2-week acclimation period. Video cameras connected to a digital multiplexer recorded the behavior of the hens. The percentages of observations performing nonnutritive pecking, feeder activity, drinking, walking, preening, head movement, and aggression were quantified for two 10-min periods at daily intervals. The FF hens spent significantly more (P < or = 0.05) time drinking than the other treatments, whereas FW hens displayed the most head movements. From d 1 through 7, FW hens walked less than ALC hens except on d 8 when FW hens walked more than ALC and FF hens. On d 4 and 6, the FW hens spent an increased amount of time preening compared with FF hens until the last few days of the molt period. For the most part, FW hens generally displayed more nonnutritive pecking than ALC and FF hens throughout the molt period. However, FW hen visits to the feeders declined as the trial proceeded, whereas ALC and FF hens generally spent more time at the feeder. In summary, the ALC diet showed potential as an alternative to FW for inducing a molt in laying hens based on reduced nonnutritive pecking behavior, head movements, and greater feeding activity.

Physiology and behavior of the hen during induced molt

Feed deprivation has been adopted by the commercial egg industry to induce molt because it is the easiest method to apply and produces the best results. Feed deprivation, however, raises concerns about animal welfare. Birds respond to long-term feed deprivation in three phases. The first phase lasts at most a few days, during which physiological and behavioral adjustments ultimately reduce protein catabolism and energy expenditure. A temporary increase in plasma corticosterone may be observed at this time. Corticosterone promotes gluconeogenesis, helping to maintain plasma glucose levels in the initial stage of the fast. The corticosterone increase may also be linked to increased activity in feed-deprived birds. Hens have been observed to manifest temporarily increased levels of alertness and activity during the first 48 h of feed deprivation. Aggressive behavior of hens also has been observed to increase briefly during the first day of feed deprivation. The second phase is the longest, during which proteins are spared and lipids are catabolized to provide energy. This phase may last several months in some species; in the chicken it can continue more than 20 d. Hens show increasing amounts of resting behavior during this phase. The third phase begins when protein catabolism accelerates. A pathological stage eventually is reached when the bird will cease activity and no longer eat. The phased response to feed deprivation optimizes a tradeoff between the need to maintain constant levels of plasma glucose to sustain activity and the need to preserve critical body structures such as muscles and organs. Hens are capable of vigorous activity throughout feed deprivation periods typical of induced molts, which do not appear to take birds beyond the second phase of fasting. Hens having undergone extended fasts may also have improved livability. Alternative induced molting methods are being sought to reduce animal welfare concerns. The methods of current interest involve alteration of feeding regimen and cause at least some body weight loss. These alternative methods should be evaluated to ensure that they do not actually make aspects of hen welfare worse compared to feed withdrawal, which might happen if hens perceive feed restriction without being allowed to progress fully into the second phase of adaptation to feed deprivation.

Behavior of white leghorn laying hens after withdrawal of feed

To approximate a commercially induced molt, feed was withdrawn (FW) from Hy-Line W-36 hens (65-wk-old) until they lost 35% of their initial body weight. Behaviors of 36 FW hens and 36 control hens were videorecorded on Days 1 to 3, 8 to 10, and 19 to 21 of FW, when FW hens reached 15, 25, and 35% body weight loss. The FW hens then were fed a pullet grower ration until Day 28 after the start of FW, whereupon they were provided a layer ration. Second cycle production of FW hens to 40 wk postmolt initiation averaged 15.5 dozen eggs/hen housed. The FW hens manifested increased aggression on the first d of FW, perhaps indicative of frustration, and then exhibited increased standing, head movement, and nonnutritive pecking on Day 2, followed by reduction of these actions on Day 3. Resting behavior was observed 24 and 40% of the time for FW hens on Days 8 to 10 and 19 to 21 of the FW period, respectively. Nonnutritive pecking was higher for FW hens than for control hens throughout the FW period. Preening was more frequent for FW hens on Days 8 to 10, probably due to skin sensitivity near the start of feather push out, which began on Day 11. Behavior during the feed withdrawal period was consistent with conservation of bodily reserves, but FW hens never lost their capability for alertness and reactivity. The FW hens had significantly lower mortality during the study than control hens (2 vs 12%, respectively).