Summary

Introduction

Beak treatment of laying hens is a „hot spot“ issue in animal welfare. In most EU countries, this prophylactic treatment is limited to a 5 year period, requires a special permit from veterinary authorities and has to be applied no later than 10 days of age. As demonstrated in many experiments (e.g. Eißele & Kraft, 1993; Lange, 1997; Damme, 2011), beak treatment of pullets is an effective means of reducing feather loss and cannibalism in laying hens. Even animal welfare organizations and politicians accept that banning beak treatment on short notice would only trade one welfare problem (pain of chicks from beak treatment) for another welfare problem (increased injuries and mortality due to cannibalism in adult hens). Two current field studies in Lower Saxony (11 farms) and Bavaria (15 farms) are designed to improve our understanding of primary causes of picking behavior in order to minimize the risk of cannibalism by optimized management practices, housing environment, nutrition, health and hygiene as well as lighting. A long-term solution should also include genetic selection (Bessei, 2012). This has been recognized as an important challenge by primary breeders, and responsible geneticists of Lohmann Tierzucht and Hendrix Genetics suggest at least 6-8 years as a realistic time window to expect significant improvements in practice from dedicated selection at the pedigree level. In the meantime, hen welfare can also be improved step by step, e.g. applying beak treatment earlier and with new techniques to minimize pain. In previous years, pullets were commonly beak treated with a hot blade up to 10 days of age on the growing farm. Nowadays, layer chick hatcheries are increasingly using the infrared (IR) technique from Nova-Tech, which had already been used for turkey poults since a number of years. The present study was designed to study the effects of different methods of beak treatment in commercial laying hens during the growing and laying period.

Experimental design

A total of 3,600 day-old chicks, representing a popular white-egg (LSL) and brown-egg (LB) variety, were obtained from a commercial hatchery (Gudendorf-Ankum) and divided into 6 experimental groups: 1/3 per strain kept as untreated control, 1/3 beak treated with infrared technique (Nova Tech) in the hatchery, 1/3 beak treated with a hot blade (Lyon Debeaker) on the rearing farm 9 days after housing.

The pullets were reared to 126 days (09.06-13.10. 2010) in a windowless house (30 x 12 m) with thermostatically controlled low pressure ventilation and spray cooling; 600 pullets per strain and treatment in a pen of 42.5 m² (8.32 m x 5.11 m); 14.1 birds /m²; nipple drinkers, chain feeders and gas brooders. Feed and water were offered ad libitum on floor level and on an elevated platform (Big Dutchman), which was easy to reach with help of an A-frame from week 3. Two thirds of the floor area had litter with heat treated soft wood shavings, one third had perches over plastic grids, with a manure belt underneath. The step-down, step-up lighting program was as described by Urselmans and Damme (2012). Prophylactic health treatment was organized by the Bavarian Poultry Health Service GGD. The following feeding program was used:



During the laying period the hens were kept in two window houses with 12 pens each, for 110 and 138 hens, respectively (8/m²). Each strain and treatment was thus tested with 496 hens in 4 replicate pens. Each pen had a litter area with wood shavings, 5 feeder pans and access to a common line of nipple drinkers.

Data recording

Rearing: Body weights were recorded from a sample of 80 birds per pen at 7, 14, 21 and 28 days of age. After 8, 12 and 18 weeks all pullets were weighed and feed consumption per pen determined. Mortality was recorded daily.

Laying period: Egg production, mortality and apparent cause of death was recorded daily throughout the 52 week laying period, average egg weight and grading results weekly, and feed consumption at the end of each 28-day period.

Plumage condition was subjectively scored by two persons at 72 weeks of age, when the test ended. The 3 point system used is illustrated below:

Subjective scoring system for plumage condition

The quality of beak treatment was also scored by two persons at 72 weeks for 474 LSL and 369 LB hens from 8 pens, using a three point classification as illustrated below.



Score 1: beak closed (upper and lower beak of same length); rounded point; no growth beyond the edges; little bone material removed.

Score 2: length of lower and upper beak differs by 2-3 mm; parts of the growth beyond the edges broken off and/or up to 1/3 of beak bone removed;

Score 3: the lower beak is significantly longer than the upper beak (> 4mm) due to regrowth; crossed beak or bony base structure cut by more than 1/3.

Results

Rearing The beak treatment with infrared technique results in heat coagulation in all tissue cultures, and the necrosis involves about 1/3 of the upper beak and ¼ of the lower beak. An important advantage of this method is that no neuromas develop, which are relevant in connection with phantom pain after amputation (Haider, 2012).

Traditional beak trimming with a hot blade cuts off approximately one third of the upper and lower beak, and cauterization seals the blood vessels and prevents bleeding. Advantages and disadvantages of the two systems are summarized in Table 1. One advantage of IR is application in the hatchery on day one, leaving the beak morphologically intact until the dead tissue drops off at about two weeks of age. Beak trimming with the traditional hot blade technique before 10 days of age on the rearing farm has no effect on feed intake during the first days. This study was intended to show to what extent beak amputation affects feed intake and growth after treatment, based on weekly weighing of samples of 80 birds per strain and treatment.









As shown in table 2, the beak treated LSL and LB pullets had a slightly lower body weight at 2-3 weeks, but the difference soon disappeared, and the beak treated groups were actually a little heavier at 18 weeks of age. Differences in feed intake (table 3) reflect not only different rates of growth, but also feeding behavior (including feed wastage) and activity. Table 4 shows larger differences in feed conversion ratio to 18 weeks of age between strains than due to beak treatment.

Mortality was low in all groups, and the differences are not statistically significant due to the small number of replicates.

Laying period

The analysis of variance showed significant differences between strains and beak treatment for henhoused egg production and mortality, expressed as production days lost due to mortality (Table 5).

IR treated LSL hens laid 7 more eggs to 72 weeks of age than untreated controls. Although total mortality (Table 6) was very low in this test, beak treatment reduced the number of production days lost due to cannibalism (cloaca picking in LB, toe picking in LSL) significantly. The lowest mortality was achieved with IR treatment, and since the mortality in the treated groups started late, the economic loss was only 1/3 compared to the untreated control groups.

Table 6 shows the performance of LSL and LB hens with and without beak treatment. High levels of production and livability indicate good bird management throughout the test. While the white-egg layers LSL were superior to the brown-egg layers in hen-day egg production and egg income over feed cost (IOFC) in all three beak treatment groups, the IR treated groups outperformed the group with conventional beak treatment and the untreated controls. Hens with IR treatment of the beak tip at day old required 25 g (LB) and 48 g (LSL) less feed per kg egg mass than untreated controls. The IR treated groups exceeded the untreated controls by 22 and 49 cents per bird, respectively, or 220 (LB) and 490 (LSL) Euro more profit per 1,000 hens housed.

The advantage of IR treatment compared to traditional beak trimming was 15 (LB) and 38 (LSL) cents per hen housed, indicating that a higher price for IR treated day-old chicks is not only justified as a contribution to hen welfare, but also by elimination of beak treatment cost on the rearing farm and higher egg income over feed cost on the layer farm.

Feather loss during the laying period

The feather condition was judged for all birds at 72 weeks of age as described above and indicates interesting differences between strains as well as beak treatment (Figures 1 and 2). The LSL hens were scored better than the LB hens, which is probably due to the fact that brown-feathered hens look partially de-feathered as soon as the brown cover feathers are lost, while the White Leghorns keep their natural color until the skin becomes visible. Doubts remain whether our scoring system is a satisfactory measure to compare functional properties of the feather cover between different breeds or gives only a visual impression.

Comparisons between beak treatment groups are consistent across breeds: 54.8% of the IR treated LSL hens had an intact feather cover at the end of test, compared to 35.0 % after traditional beak trimming and only 15.7% of the untreated control. The differences due to beak treatment were less consistent in the LB groups, where conventional beak treatment was apparently more effective than IR to prevent feather damage due to picking, but again the untreated control had the poorest feather condition.

Quality of beak treatment

An intact beak of chickens is hook-shaped and pointed. The upper beak is longer than the lower beak and enables the hen to pluck and pull, select feed particles and to preen. The organ at the tip of the beak plays an important role for these functions.

Therefore, the goal of any beak treatment must be to destroy as little live nerve tissue as possible and to induce quick recovery, while reducing the frequency of aggressive picking. The treatment should minimize pain and interfere as little as possible with feed selection, feed intake and preening, but prevent the misuse of the beak as a pair of tweezers to pull feathers of other hens. The goal is therefore a well closed beak without sharp or pointed ends. The quality and uniformity of beak treatment with the hot blade depends largely on the experience of the people doing the job. Additional factors to be taken into account with IR treatment are the size and uniformity of the chicks and adjustment of the machine.

The beak quality assessment at the end of the laying period (Figure 3) indicates that different strains may respond different to beak treatment, and these effects can be additive.



The benefit of IR beak treatment, compared to conventional hot blade treatment, is more obvious for LSL than for LB hens. To what extent these differences reflect genetic differences in bone formation and potential for re-growth cannot be answered from a comparison of hens from a single hatch day, followed by beak treatment with the same setting of equipment.

As a basis for future refinement of the IR technique, more records on chick size (or age of parent flock) and settings of IR equipment should be collected for breeder flocks of different age and correlated with records on beak quality of adult hens. A realistic short-term target should be more flocks with similar beak quality as the IR treated LSL hens in this test, while geneticists continue to select for reduced picking and non-genetic factors contributing to picking are controlled as much as possible.