Influence of toe-clipping and stocking density on laying hen performance

Effects of different claw-shortening devices on claw condition, fear, stress, and feather coverage of layer breeders

Natural mating colony cage systems for parent-stock layer breeders have been widely adopted by many commercial farms in China. However, the environment is still relatively barren, so enrichment devices such as claw abrasives can be provided. Hens living in wire cages lack the opportunity to abrade their claws, resulting in uncontrolled claw growth. The objective of this study was to investigate the effects of claw abrasive devices (CADs). Three different CADs were investigated: abrasive strips (T1), metal plates with holes (T2) and rubber mats with grooves (T3); cages without CADs acted as controls (T4). Claw length and sharpness, foot health, feather coverage, fear and physiological stress and mortality of the layer breeders were evaluated. Twelve replicates were used for each treatment, a total of 48 identical cages. Results showed that CADs had significant effects on claw length and sharpness of both hens and roosters. Birds in the T1 group had the shortest claw length and bluntest claw sharpness at 22, 32, 42, and 52 wk of age (P < 0.05). T1, T2, and T3 had higher scores for claw condition and significantly better overall plumage condition on the back and rump than T4 (P < 0.05). Hens in the T4 group were more susceptible to the tonic immobility, novel object, and avoidance distance tests. No significant differences were found between groups in concentration of triiodothyronine, thyroxine or 5-HT, except a significantly higher concentration of corticosterone in T4 compared to T1, T2, and T3 (P < 0.05). Overall mortality and mortality from cannibalism were both significantly higher in T4 than in T1, T2, and T3 (P < 0.05). In conclusion, hens with access to CADs during the laying period had shorter and blunter claws, less damaged plumage, a lower plasma corticosterone secretion and mortality rate and were less fearful.

The Effect of Claw and Beak Reduction on Growth Parameters and Fearfulness of Two Leghorn Strains

Commercial equipment used by the turkey industry at hatch sterilizes the germinal tissue of the claw with microwave energy and the beak tissue with infrared energy. This effectively trims the claws and beaks of the birds. Two strains of Leghorn chicks (1,200 each strain) were utilized to test this technique on chickens. Half were subjected to the claw reduction (RC) technique at hatch, and half retained intact claws (IC). The beaks of one-third of the birds in the claw treatments were reduced (BT) at hatch using the infrared technique, one-third were precision trimmed at 7 d, and one-third were not trimmed (IB). Body weight, weight gain, feed intake, feed conversion, mortality, and fearfulness were measured. Rearing followed standard commercial feeding and husbandry procedures. The RC birds had significantly lower BW, except from 3 to 6 wk, and had significantly lower feed consumption from 8 to 18 wk. The 1 d BT birds experienced significantly lower BW from 3 to 14 wk and ate less total feed by 4 wk. Mortality was less than 2.1% for all treatments. From 6 to 8 wk, fearfulness score (a subjective scale of 1 to 10) peaked at 8 to 10 for IC birds and 3 to 4 for RC birds. By 16 to 18 wk, fearfulness score subsided to 2 to 3 for RC and 6 to 8 for IC. Beak trimming and reduction of claw growth at hatch allowed pullets to be grown to sexual maturity on less feed and with a lower level of observed fearfulness using standard husbandry practices.

Effects of body weight groupings on productivity, feather loss, and nervousness of caged hens

Two experiments compared performance traits, feather loss, and nervousness of hens kept in contrasting homogeneous and heterogeneous body weight groupings. In addition, 15-day periods of daily uterine palpating vs nonpalpating for an egg in the uterus were compared for effects on egg production. Eighteen-wk-old pullets were weighed and characterized as light, medium, or heavy and housed in laying cages at 19 wk for a 50-wk production period. In Experiment 1, two hens were placed in each cage and there were three treatment groups: both light (L), mixed or 1 heavy and 1 light (X), and both heavy (H). In Experiment 2, three pullets were used per cage; a medium-weight group (M) was included and mixed cages included 1 heavy, 1 medium, and 1 light weight bird. In an ancillary experiment, 50-wk-old hens were also palpated or not palpated for an egg in the uterus over a single 15-day period. Results indicated that differences that were present in initial body weight groups persisted over the 50-wk period in Experiments 1 and 2 with no effect of weight grouping on body weight gain, egg production, and livability. Differences that were associated with weight groups were: age at sexual maturity, egg weight, egg mass, and nervousness score. No differences in mean feather scores were present among weight groups. Comparisons between individual hens of the same relative weight but kept in homogeneous or heterogeneous weight groups failed to indicate competitive advantages or disadvantages in egg production, feathering, and nervousness scores. No significant associations were found between nervousness scores of individual hens and other traits except for total body weight gain in Experiment 1, in which individuals that gained more were less nervous in the X groups (r = -.55). Palpating hens daily for two 15-day periods significantly increased hen-day egg production in Experiment 2 and nonsignificantly in Experiment 1, with no influence of palpation on hen-day egg production, egg weight, or egg mass in the ancillary experiment.

Effects of population size, floor space, and feeder space upon productive performance, external appearance, and plasma corticosterone concentration of laying hens

Effects were studied of population size, floor area, and feeder space per hen on variables associated with egg production and corticosterone level. A total of 408 White Leghorn-type laying hens was used in this study. Three treatments were observed: 5 hens per cage with 8.6 cm feeder space per hen, 5 hens per cage with 12 cm feeder space per hen, and 7 hens per cage with 8.6 cm feeder space per hen. Both 5-hen treatments had 420 cm2 of cage area per hen, while the 7-hen treatment had 300 cm2. Increased population size, reduced feeder space, and reduced floor area per hen resulted in a significant (P less than .01) decline in percent egg production. Restriction of feeder space was correlated with reduced feed consumption and mortality but not feed conversion, weight gain, and egg size. As cage space allowance increased, feed consumption and weight gain were higher, whereas mortality, feed conversion, and egg weight were lower. No significant (P greater than .05) differences in shell thickness, specific gravity, Haugh unit, throat skin ateromata, claw length, and corticosterone level were observed. Plumage condition and foot health were improved only when floor area allowances increased.

An economic analysis of performance data from toe-clipped laying hens housed at variable stocking densities

Data from a previously reported study investigating the interaction of toe-clipping and stocking density on laying-hen performance were subjected to economic analyses to determine optimal profit-producing combinations of these two management practices. In three separate trials, toe-clipped (TC) and intact (IN) pullets were examined at caging densities of either 4 (465 cm2/hen) or 5 (372 cm2/hen) birds per cage. In each trial, beginning at 22 wk of age, hen production performance (hen-day egg production, hen-housed egg production, feed consumption, body weight, and mortality) was assessed for 12 28-day periods of lay. Performance criteria were averaged over all trials and used to determine per cage returns ($) above feed and pullet rearing costs (irrespective of fixed costs) and per cage profits (gross returns minus total costs) for the four treatment combinations. Economic analyses were also adjusted for hatchery toe-clipping costs. Profits (or losses) from each toe treatment stocking-density combination were calculated under variable egg and feed prices. At a blended egg price of $.35/doz, all cage systems lost money. Housing hen TC, 5/cage, yielded the greatest profits or least losses in 76% of the toe treatment stocking-density combinations studied. Economic returns were greatest for TC hens, 5/cage, at an egg price of $.55/doz when feed costs ranged from $140 to $230/ton and at egg prices higher than $.55/doz, regardless of feed prices. However, when these price combinations exist, housing hens IN, 4/cage is more profitable than housing hens TC, 4/cage.(ABSTRACT TRUNCATED AT 250 WORDS)