Research Note: Differences in the pecking behavior of turkey hens in proximity to the feeding pan depending on their beak condition

Abstract

The present study aimed to provide further insight on different pecking behavior of beak-trimmed and untrimmed turkey hens in proximity to the feeding pan. Investigations were carried out in 4 housing compartments with female fattening turkeys where video were recorded and evaluated with regard to 4 different types of (pecking-) behavior (feeding, pecking on the ground, pecking at conspecifics, being pecked) observed in 1 focal animal in proximity to each feeding pan. Concerning the median duration, there were only small differences between the animals with different beak conditions. Pecking behavior varied in how many animals exhibited ‘pecking on the ground’ with more turkeys with intact beaks showing this activity in proximity to the feeding pan with a slightly increased median duration (0:06 vs. 0:04 min). Further discrepancies were observed in the maximum duration of recorded behaviors, as there were animals with intact beaks that showed “pecking on the ground” (4:09 vs. 2:54 min), “pecking at conspecifics” (3:46 vs. 1:25 min), and were “being pecked” (0:52 vs. 0:35 min) for a longer period of time. Based on this result, however, it can be assumed that especially individual animals with an intact beak forage more intensively and perform some pecking behaviors, which include injurious pecking, with longer duration in proximity to the feeding pan.

INTRODUCTION

It is assumed that turkeys in the feeding area, and thus in direct connection with feed intake, increasingly peck at each other (Spindler and Hartung, 2007). This can lead to injurious pecking, which can cause severe injuries and pain for the animals. To inhibit this undesirable behavior respectively to reduce negative consequences of injurious pecking, beak trimming is used as common practice (e.g., in Europe and the United States). However, the procedure of beak trimming is considered as a partial amputation, reported to induce chronic pain and to reduce sensory feedback as well as feed intake (Marchant-Forde et al., 2008). Therefore, in Germany beak trimming has been prohibited since 2008 in organic turkey fattening and is discussed to be banned in future in conventionally reared animals as well (Grün et al., 2021).

Especially in flocks of turkeys, whose untrimmed beaks cause damage to the plumage or skin of their conspecifics more easily, injurious pecking may increase and lead to an outbreak in the flock representing a widespread animal welfare issue (Schulze-Bisping, 2015). As massively affected birds often have to be culled or their carcasses are downgraded at processing, this behavior should be detected as well as prevented with suitable countermeasures, such as the offer of additional environmental enrichment (Hafez, 1999; Marchewka et al., 2013).

The causes of injurious pecking are multifactorial; for instance, the influence of flock size, stocking density, poor environmental complexity, poor climate, feeding aspects, and genetics are discussed (Dalton et al., 2013; Marchewka et al., 2013). Furthermore, there is evidence that limited resources like drinkers can lead to agonistic behavior or injurious pecking (Schäfers and Kemper, 2023).

To gain further insight into how beak-trimmed and untrimmed animals behave with regard to other limited resources and in specific places in the barn, this study aimed to investigate different pecking behaviors of turkey hens with intact and trimmed beaks in proximity to the feeding pan.

MATERIALS AND METHODS

Ethics Statement

All of the animals were housed in accordance with EU (European Directive 2008/120/EC) and German national law (Tierschutzgesetz, Tierschutz-Nutztierhaltungs-Verordnung). In compliance with European Directive 2010/63/EC Article 1 5. (f), the present study did not imply any invasive procedure or treatment to the animals.

Animals and Data Collection

In an experimental barn, turkey hens (British United Turkey, B.U.T. 6; Aviagen, Huntsville, AL) were housed in four 35m² compartments (143 animals each, 2 compartments with beak-intact birds and 2 with beak-trimmed birds) under practical housing conditions (stocking density 48 kg/m²). Each compartment was equipped with 2 drinkers and 2 feeding pans. Turkey hens were fed ad libitum with a 5-phase standard feed program according to the recommendations of the breeder (Moorgut Kartzfehn). A 18-h lighting schedule was applied (from 6 am to 10 pm) with dark phases for resting integrated both at midday (from 12 to 1 pm) and in the early evening (from 6 to 7 pm).

From the 6th to the 16th wk of life, videos were taken in proximity to both offered feeding pans (observed area: one hen's body length in proximity to the feeding pan, Figure 1) from 14:00 to 16:00 two d a week via video cameras (5MP Basic Set, Berghoch, Hartford Electronics GmbH, Dortmund, Germany).

Figure 1.

Picture of the video camera view with the observation area marked by an orange circle. Picture by Karolin Skiba.

One focal animal was observed at each feeder (total n = 8 per week of life, overall 336 animals with intact beaks and 336 with trimmed ones). At 4 points of time at 30-min intervals, the duration of the following behaviors in the observed area was recorded:

• ­Feeding (F) (head of the turkey hen was in the feeding pan)
• ­Pecking on the ground (GP) (within one animal length the hen pecked on the ground)
• ­Pecking at conspecifics (CP) (aggressive head-/feather-pecking/cannibalism towards a conspecific)
• ­Being pecked (SP) (agressive head-/feather-pecking/cannibalism towards a focal animal).

For each observation point, a randomly selected turkey hen that was currently in the observation area was selected and its behavior recorded by 1 researcher. A behavior was considered to have been ended when the focal animal stopped the observed behavior for 5 s. Finally, 25 time points of the video recordings could not be analyzed for various reasons. The first group of excluded data was due to no animal was in the observed area in proximity to the feeding pan (n = 10). The second reason for excluding was a poor quality of the recordings (n = 3), and the third exclusion criterion was if a turkey hen was visible in the observed area at starting point, but did not stay there (n = 12). Thus, at 647 observation points the behavior of a focal animal was documented. Data were checked for normal distribution using histograms and Q-Q plots and evaluated descriptively. Due to non-normally distributed data the median value for each behavior was determined, furthermore interquartile range (IQR) and maximum duration.

RESULTS AND DISCUSSION

This study investigating the different pecking behavior of turkey hens with intact and trimmed beaks in feeding situations showed a high variation in the duration of the general presence in proximity to the feeding pan (Table 1). Durations of presence ranged from 0:01 to 11:16 min in animals with intact beaks, and up to 29:38 min in those with trimmed ones. The median feeding duration only differed slightly between the 2 groups (intact: 0:39 min, IQR 0:15–1:21; trimmed: 0:35 min; IQR 0:12–1:32). There was also no notable difference in the median duration of pecking at conspecifics (CP) (0:05/0:04 min) and being pecked (SP) (0:05/0:06 min). But, the behavior of pecking on the ground (GP) varied between the observed animals. Overall, more turkey hens with intact beaks (n = 169 vs. 142) were observed performing (GP) in proximity to the feeding pan. The median duration of GP of hens with intact beaks (0:06 min; IQR 0:02–0:16) was also slightly higher than that recorded in the animals with trimmed beaks (0:04 min; IQR 0:02–0:12). Based on this result, it can be assumed that animals with intact beaks forage more intensively.

Table 1.

Duration of recorded behaviors in proximity to the feeding pan for turkey hens with intact (n = 325) and trimmed (n = 322) beaks. The minimum duration of the observed behaviors was 0:01 min in each case and is therefore not listed.

Behavior	Beak condition	n	Median (min)	IQR (min)	Max (min)
General presence	Intact	325 (100%)	0:42	0:08–1:45	11:16
	Trimmed	322 (100%)	0:42	0:13–2:01	29:38
Feeding (F)	Intact	202 (62.1%)	0:39	0:15–1:21	6:36
	Trimmed	201 (62.4%)	0:35	0:12–1:32	6:12
Pecking on the ground (GP)	Intact	169 (52.0%)	0:06	0:02–0:16	4:09
	Trimmed	142 (44.0%)	0:04	0:02–0:12	2:54
Pecking at conspecifics (CP)	Intact	108 (33.2%)	0:05	0:02–0:13	3:46
	Trimmed	146 (45.3%)	0:04	0:02–0:15	1:25
Being pecked (SP)	Intact	83 (25.5%)	0:05	0:02–0:08	0:52
	Trimmed	88 (27.3%)	0:06	0:02–0:09	0:35

It is known that turkeys show intensive foraging and generally exhibit a high level of pecking activity, which in some cases is also displayed regardless of the state of hunger (Reiter, 2009). In the present study, this higher pecking activity performing GP in proximity to the feeding pan was found more in the turkeys with intact beaks than in those with trimmed ones. This was perhaps due to the condition of the beak. In practice, it is often discussed in this regard that animals with intact beaks lose food grains offered more frequently or tend to waste food grains. Accordingly, pecking on the ground would represent the search for this food or lost grains, although the edges of the feeding pans in the compartments studied had comparatively high edges.

The results of the maximum duration of some behaviors performed by individual birds showed considerable differences. When analyzing GP, the maximum duration shown by a turkey hen with an intact beak was 4:09 min and for a trimmed one 2:54 min. At 0:52 min, the maximum duration of the behavior SP in the turkey hens with intact beaks was also longer than that measured in the trimmed animals (SP trimmed = 0.35 min). The duration of CP shown was even more than twice as long in birds with an intact beak. One turkey hen in this untrimmed group showed CP over a period of 3:46 min. In contrast, the longest CP phase in the animals with trimmed beaks lasted 1:25 min. Thus, the groups showed differences in the duration of CP behavior performed, with the trimmed hens achieving a higher total duration than the birds with intact beaks (untrimmed = 22.16 min; trimmed = 26.44 min). Overall, more animals with trimmed beaks were observed performing CP in proximity to the feeding pan (n = 146) compared to animals with intact beaks (n = 108).

In the present study, the pecking at conspecifics CP was classified as injurious pecking. According to earlier studies, this injurious pecking includes feather pecking and cannibalism (Erasmus, 2018), which are thought to be related to an “appetitive component of exploratory motivation” of the birds examining their environment intensively (Rudkin, 2022). Together with the longer and more frequent pecking of the animals with intact beaks on the ground (GP), the likewise extended duration of the CP might be an increased execution of such an “appetitive component of exploration motivation.” Of course, it has to be kept in mind that these maximum durations were shown by individual animals and not by the average group.

A correlation might be assumed between the more frequent and more severe injuries as well as the higher mortality rates in the untrimmed group and the behavior of CP performed by individual animals, which in some cases lasted considerably longer. In the present study, the hens with intact beaks showed a higher mortality rate of 10.2%, 8.4% of which were losses due to pecking, than in birds with trimmed beaks with 3.2% losses, 2.8% of which were due to pecking. In order to find out whether the increased mortality rate in the untrimmed birds was related to the increased duration of pecking conspecifics (CP) performed by individual animals, or to know whether this behavior differed between the 2 groups in the entire barn, further investigations need to be carried out. The existing data from this study are too limited, as they represent a “snapshot” of a focus animal in a defined area.

Although an increased number of severe injuries and higher losses due to injurious pecking occurred in the turkey hen flocks with intact beaks, the results from this study do not indicate that these were related to the average duration of certain behaviors at the feeding pen. At least in the period observed here, there was no difference in the average duration of pecking at conspecifics or being pecked by the tracked focal animals. Whether the number and severity of injuries caused by injurious pecking are related to the maximum duration (of an individual animal) of a performed misbehavior in proximity to the feeding pan should be investigated in more detail in further studies.

Funding

Open Access funding enabled and organized by Projekt DEAL.