Intact broiler breeders are the future
The number of mutilations in breeders has decreased considerably in recent years. More research is needed to phase out the remaining treatment: hind toe clipping in males. It is expected that this should be possible in the near future with appropriate management.
Until the turn of the century, mutilations were commonplace in broiler breeder males and females. Day-old males were treated on the comb, beak (upper and lower), spur (left and right), and toes (left and right hind and sometimes also the inner toe) resulting in 7 or 9 open wounds. Females were only treated on the upper and lower beak.
The reason for dubbing the combs was that in winter, they could freeze, leading to inflammation and mortality in males. Stopping with comb clipping (or dubbing) in broiler breeder parents was relatively quickly implemented because it had benefits for separated sex feeding. Males with intact combs were, due to the grill, less able to reach the feed in the female feeders.
Burning the spurs was done because they could become very sharp, causing wounds to the back and thighs of the females. This procedure was carried out by applying a hot point against the spurs of the day-old males. From around 2000, this procedure was successfully stopped, mainly due to selection procedures by the breeding companies resulting in softer and blunter spurs.
Beak trimming was standard practice in most countries in the world. In the Netherlands, this mutilation has been prohibited since 1 January 2019 for females of fast-growing broiler breeders. Beak treatment for males has since 1 September 2023 no longer been allowed. Interesting is that no adjusted management was needed to change to breeders with intact beaks. This was a very good (or bad) example that sometimes the industry is adopting procedures for no good reason. Discussion is needed to reconsider certain actions.
In the Netherlands, the last remaining treatment for males is the removal of the hind toes of day-old chicks.
Beak trimming in breeders
During a fact-finding mission to Poland and the United Kingdom in 2011, it was found that it is possible to keep broiler breeders with intact beaks. After the study trip, an on-farm experiment was conducted in the Netherlands and, during this experiment, Ross 308 breeder pullets were raised with intact or trimmed beaks. At a commercial farm with 4 similar rearing houses, female pullets with intact beaks were placed in 2 houses and females with treated beaks in 2 other houses. Behavioural observations showed that pullets with intact beaks resulted in fewer stereotypical pecking at walls (Table 1). Additionally, mortality (including culling) was lower, and bodyweight uniformity was improved at the end of the rearing period.
Males with intact hind toes
In 2016, an on-farm study with fast-growing breeders was conducted with one house with males with intact hind toes and one house with treated hind toes. At 25 weeks of age, only 7% males (standard was 9% males) were present to prevent over-mating and damaging the females. The total mortality and egg production between the houses did not differ, but in the house with males with intact toes, mortality in females due to flank injuries was 1.5 percentage points higher (2% compared to 0.5%) than in the house with males with treated hind toes.
Subsequently, in 2019, on a commercial farm with fast-growing breeders, a house was used with males with intact hind toes on one side and males with treated hind toes on the other side. From 27 weeks of age, there was mortality among the females due to flank injuries, which increased significantly after 32 weeks of age. Therefore, at 37 weeks of age, the decision was made to trim the nails of the hind toes. After this intervention, mortality due to flank injuries decreased rapidly, but ultimately, the total female mortality at the end of the laying period was 11.3% and 22.8% for the flocks with treated and untreated males, respectively.
The female mortality due to flank injuries at 60 weeks of age was 0% and 8.9% for the flocks with treated and untreated males, respectively. The significant difference between the first and second farm was the percentage of males at the start of the laying period, namely 7.1% and 8.7%, respectively. It is expected that the higher percentage of males had more (forced) matings, resulting in more injuries.
Experiences in Scandinavia
In 2021, a fact-finding mission to Scandinavia was organised to gain more knowledge about their experiences with males with intact hind toes. From this trip it was concluded that it appears feasible to keep males with intact hind toes. In Sweden, breeders within one integration completely stopped from September 2018 with the hind toes treatment. In Norway, breeders have not applied the treatment for the past 3 years, while in Denmark, various trial groups have been followed for the past 2 years. Recent information showed that 60% of the flocks have males with intact toes and this will be 100% in 2025.
In none of these countries is stopping with the hind toe treatment compelled by regulations, but rather to prevent mortality (and especially culling) among males, as well as to mitigate male quality and concerns about the use of antibiotics. The experiences so far have been predominantly positive: male quality has improved, and there is less mortality (and culling) among males due to leg problems during the rearing phase. Even during the laying period, there are hardly any issues with mortality and production (number of eggs, fertility and mortality).
Recent on-farm study
Based on the experiences form Scandinavia, an on-farm study in the Netherlands was conducted to investigate the effect of males with intact hind toes on mortality, feather cover (females), and reproduction performance. For this study, a total of 15 different commercial breeder farms spread across the Netherlands were involved. Each farm had at least 1 house with males with intact hind toes to compare to houses with males with treated toes.
Out of these 15 farms, 10 had Ross 308 (regular fast-growing) broiler breeders, and 5 had Hubbard JA57 females (slow-growing) with regular (fast-growing) M77 males. The males with treated and intact hind toes were reared together in the same house or compartment until 20 weeks of age. At the end of the rearing period, data regarding mortality (and culling) of males with treated and intact hind toes were collected. During the laying period, the feather quality and any thigh skin damage of 60 females per participating house were scored at 28, 35, and 45 weeks of age.
Production performance results of the flocks (egg production, feed consumption, incubation traits and mortality) were recorded. Additionally, the mortality specifically due to thigh injuries was noted. It was predetermined within the project that, if there was excessive mortality (>1%) due to flank injuries, the nails of the males would be clipped to prevent further mortality.
Results rearing phase
The mortality (and culling) throughout the entire rearing period was significantly (6%) lower in Ross 308 males with untreated hind toes than in males with treated hind toes. Most of the mortality (approximately 90-95%) was caused by leg health issues. These were usually males with inflamed footpads and hocks due to staphylococci infections and crooked backs due to streptococcal infections. This phenomenon was also observed in Scandinavia. The clear difference in the number of inflammations on footpads, heels and backs may have been caused by the open wounds created immediately after hatching in the hatchery. Removing a portion of hind toes is an invasive procedure due to the wound, which can introduce bacteria. For the Hubbard M77 males, the mortality (and culling) during the rearing phase was 32.1% and 25.3% for treated and untreated males, respectively.
The relatively minor intervention on day-old chicks seems to have a long-term effect on the (leg) health of the males.
Feather cover females laying phase
At 28 weeks of age, there were no differences in feather cover among the Ross 308 females kept with treated or untreated males. However, the average feathering score at 35 and 45 weeks of age was higher (worse) on the thighs for the Ross 308 females kept with untreated males (Figure 1).No differences were found in feathering at any of the ages for the Hubbard JA57 females kept with treated or untreated males.
Thigh damage of females laying phase
For the Ross 308 females kept with untreated males, more minor flank injuries were observed at 28 and 45 weeks of age. At 35 weeks of age, more severe injuries (7.4% vs. 1.7%) were found on the thighs of the Ross 308 females. For the Hubbard females, at 35 and 45 weeks of age, 5-10% more birds were observed with minor injuries on the thighs in the flocks with untreated males.
Reproduction performance
For the Ross 308 females, there was no difference in total mortality at 30 and 60 weeks of age between flocks kept with treated and untreated males (Table 2). However, at 60 weeks of age, there was a tendency towards higher mortality due to flank injuries in Ross 308 females kept with untreated males (0.4% vs. 0%). No other differences in production performances (egg production, fertility, etc.) were found for the Ross 308 and Hubbard JA57 females.
For the Hubbard JA57 females, total mortality at 60 weeks of age was higher when kept with untreated males (8.6% vs. 4.1%). This mortality occurred in the second half of the laying phase and was not caused by severe thigh injuries (Figure 2).
It is not entirely clear what caused this increased mortality, but it may be related to pecking behavior. The minor thigh injuries at a later age may have triggered pecking behavior, ultimately leading to mortality due to pecking and E. Coli infection.
Practical implications
This practical study demonstrates that keeping males with intact toes, both for Ross 308 and Hubbard JA57 parent stock, is currently not feasible under the prevailing conditions without adverse effects on feathering, mortality and female welfare. More research is needed to keep intact broiler breeder males in an animal-friendly way. This is why this research was continued with greater emphasis on adjusted management: starting with a reduced percentage of males (approx. 6-7%), lower light intensity (between 5 and 10 lux), and lower male weights (200-300g) at onset of lay. It is expected that we will be able to keep males intact in the future with good welfare, health and production performance.
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