Research Note: Beak morphology of infrared beak-treated laying hens and its impact on production and welfare.

Despite previous research on the impacts of beak treatment on laying hens, little information exists regarding how variation in beak morphology that can occur following beak treatment affects production, behavior, and welfare. Following infrared beak treatment (IRBT), variations in beak shape, such as a shovel beak (bottom beak longer than top), cracks (Cr), or bubbles (B) may occur if the IRBT equipment is damaged or if a quality control program is not followed at the hatchery. This study aimed to determine if variations in beak morphology post-IRBT impacted laying hen production or welfare. Infrared beak-treated Lohmann LSL-Lite hens (n = 80) were selected from a 56-wk-old flock and randomly assigned into 1 of 8 treatments: flush beak (control), shovel beak extending 0-1 mm (SB0-1), 1-2 mm (SB1-2), 2-3 mm (SB2-3), 3-4 mm (SB3-4), or >4 mm (SB > 4), Cr, or B. Hens were housed in individual cages for 4 wk and production (body weight, feed intake, egg production, and egg quality), and welfare (behavior and histology) parameters were evaluated. Consumption of different particle sizes was assessed by measuring feed particle size of refused feed. Data were analyzed as a one-way ANOVA, in a completely randomized design using PROC GLM (SAS 9.4). The results indicated that the beak morphologies examined had minimal effects on the production or welfare of the hens. Histological assessment did not show the presence of neuromas in the beak tissue, suggesting that the hens were not experiencing chronic pain from the IRBT procedure.

The effect of beak tissue sloughing and post-treatment beak shape on the productivity of infrared beak-treated layer pullets and hens.

Infrared beak treatment (IRBT) results in a change in beak shape; however, it is unclear what effect variations in post-treatment beak shape have on young pullets. Additionally, the impact of sloughing of the treated beak tissue is not fully understood. Two experiments were conducted to determine the effects of beak tissue sloughing and post-treatment beak shape on the productivity of infrared beak-treated Lohmann Brown (LB) and Lohmann LSL-Lite (LW) pullets and hens. Birds were treated on day of hatch and IRBT equipment settings were adjusted to create 4 specific beak shapes: shovel (SHV), step (STP), standard (STAN), and an untreated sham control (C). Experiment 1 pullets (n = 160) were housed in cages from 1 to 29 d of age and had access to water through chick founts or 360° nipple drinkers (2 replicate cages per treatment). Data collected included body weight (BW), feed intake (FI), feed efficiency (FE), and water disappearance (WD). Experiment 2 pullets (n = 640) were housed in floor pens from 1 d to 18 wk of age (2 replicate pens per treatment) then conventional cages during the laying period (6 replicate cages per treatment). Data collected included BW, FI, egg production, and egg quality. Data were analyzed using PROC MIXED (SAS® 9.4) and differences were significant when P ≤ 0.05. During early life, the IRBT treatments and sloughing had minor effects on FI, FE, and BW. At 4 wk of age, STAN pullets were lighter than C pullets; however, differences were no longer apparent after this age. Pullets with STP or STAN beak shapes had lower WD than C pullets when allowed access to water via nipple drinkers but this did not result in reduced growth. Throughout the laying period, SHV hens laid more saleable eggs than C hens, with no other effects on production. Overall, variations in beak shape and sloughing of the beak tissue had minimal impacts on the productivity of LW and LB pullets and hens.

The impact of beak tissue sloughing and beak shape variation on the behavior and welfare of infrared beak-treated layer pullets and hens.

This research examined how infrared beak treatment (IRBT), sloughing of the treated beak tissue, and the variations in beak shape that can occur post-IRBT impact the welfare and mortality of Lohmann LSL-Lite (LW) and Lohmann Brown (LB) pullets and hens. Two experiments were conducted and birds for both experiments were treated on the day of hatch. IRBT equipment settings were adjusted to create 4 specific beak shapes: shovel (SHV), step (STP), standard (STAN), and an untreated sham control (C). Experiment 1 pullets (n = 80 per strain) were reared in bioassay cages from 1 to 29 D of age (4 replicates per treatment). Data collected included time and presence of beak sloughing, pecking force, behavioral expression, and mortality. Experiment 2 pullets (n = 320 per strain) were reared in floor pens from 1 D to 18 wk of age (2 replicates per treatment) and then conventional cages from 18 to 60 wk of age (6 replicates per treatment). Data collected for Experiment 2 included behavioral expression, feather cover, comb damage, and mortality. Data were analyzed using PROC MIXED (SAS® 9.4) with Tukey's test to separate means. Differences were significant when P ≤ 0.05. IRBT and sloughing had no effect on pecking force or mortality throughout rearing. The variations in post-IRBT beak shape had minor effects on behavior. During rearing, STAN pullets were more active than C pullets but STP and STAN pullets performed less exploratory pecking. During the laying period, SHV and STP hens preened more than C hens. The IRBT treatments, regardless of beak shape, reduced feather loss, comb damage, and cannibalism-related mortality during the laying period. Overall, the results indicate that LW and LB pullets and hens can cope with the change in beak shape that occurs with IRBT, and that welfare is not negatively impacted if some variation in beak shape occurs.

Avian magnetic compass can be tuned to anomalously low magnetic intensities.

The avian magnetic compass works in a fairly narrow functional window around the intensity of the local geomagnetic field, but adjusts to intensities outside this range when birds experience these new intensities for a certain time. In the past, the geomagnetic field has often been much weaker than at present. To find out whether birds can obtain directional information from a weak magnetic field, we studied spontaneous orientation preferences of migratory robins in a 4 µT field (i.e. a field of less than 10 per cent of the local intensity of 47 µT). Birds can adjust to this low intensity: they turned out to be disoriented under 4 µT after a pre-exposure time of 8 h to 4 µT, but were able to orient in this field after a total exposure time of 17 h. This demonstrates a considerable plasticity of the avian magnetic compass. Orientation in the 4 µT field was not affected by local anaesthesia of the upper beak, but was disrupted by a radiofrequency magnetic field of 1.315 MHz, 480 nT, suggesting that a radical-pair mechanism still provides the directional information in the low magnetic field. This is in agreement with the idea that the avian magnetic compass may have developed already in the Mesozoic in the common ancestor of modern birds.

The magnetite-based receptors in the beak of birds and their role in avian navigation.

Iron-rich structures have been described in the beak of homing pigeons, chickens and several species of migratory birds and interpreted as magnetoreceptors. Here, we will briefly review findings associated with these receptors that throw light on their nature, their function and their role in avian navigation. Electrophysiological recordings from the ophthalmic nerve, behavioral studies and a ZENK-study indicate that the trigeminal system, the nerves innervating the beak, mediate information on magnetic changes, with the electrophysiological study suggesting that these are changes in intensity. Behavioral studies support the involvement of magnetite and the trigeminal system in magnetoreception, but clearly show that the inclination compass normally used by birds represents a separate system. However, if this compass is disrupted by certain light conditions, migrating birds show 'fixed direction' responses to the magnetic field, which originate in the receptors in the beak. Together, these findings point out that there are magnetite-based magnetoreceptors located in the upper beak close to the skin. Their natural function appears to be recording magnetic intensity and thus providing one component of the multi-factorial 'navigational map' of birds.

Seasonal variation in sensitivity of the photoperiodic response system in the subtropical tree sparrow (Passer montanus).

We investigated seasonal variations in response to photoperiods in subtropical tree sparrow (Passer montanus), by examining the effects of long and short days on stimulation of response and termination of refractoriness, respectively. We also assessed whether photoperiodic effects were sex dependent. In one study, wild sparrows were transferred in each month of the year to artificial long days (14L/10D) for 12 weeks. Birds transferred from November to March (female) or April (male) showed gradual increase in gonadal growth and darkening of bill color, while those transferred from April (female) or May (male) to July underwent gradual regression in the above responses. Moult in the wing primaries and body feathers progressed with gonadal regression and the birds transferred from April/May to October exhibited gradual increase and decrease in feathers moult. In another study, 6 weeks of short day (9L/15D) exposure could recover responsivity to long days in refractory birds. Male and female birds responded almost in similar fashion with some variations. Overall, our results show a gradual change over seasons in responsiveness of the endogenous response system to stimulatory effects of long day length. They suggest roles of both long and short day lengths in regulation of seasonal cycles in subtropical tree sparrows.

Different effects of infrared and one-half hot blade beak trimming on beak topography and growth.

This study examined the effects of infrared beak treatment (IR-BT) and hot blade beak trimming (HB-BT) on beak length and production in laying hen pullets. Seventy-two 1-d-old birds were randomly assigned to the HB-BT, IR-BT, or control group. Birds were pair housed by treatment, and beak images and production indices were obtained posttreatment at fixed intervals for 10 wk. Immediately after treatment, HB-BT beaks were shorter than control or IR-BT beaks (P < 0.01), whereas control and IR-BT beaks remained comparable in length until the onset of tissue degeneration and erosion of the IR-BT beaks at 1 to 2 wk posttreatment. At wk 2 posttreatment, beaks were longest in control birds, intermediate in IR-BT birds, and shortest in HB-BT birds (P < 0.01). Thereafter, an increase in beak length in all treatments was observed over time (P < 0.01), but HB-BT beaks had the greatest regrowth. The beak length of birds in the HB-BT group was similar to that of birds in the IR-BT group from wk 3 to 8, and then grew longer at wk 9 and 10 posttreatment (P < 0.01). The effects of treatments on BW emerged at d 5 posttreatment. The BW of birds in the HB-BT group was suppressed up to and including wk 9 posttreatment compared with that of control birds (P < 0.05) and was significantly lower than that of birds in the IR-BT group between 2 and 4 wk posttreatment (P < 0.05). Birds in the IR-BT group did not differ from control birds after wk 3 posttreatment (P < 0.05). By the final week of the study, differences in BW across treatments were no longer apparent (P > 0.05). For the most part, feed intake was higher in control birds, intermediate in birds in the IR-BT group, and lowest in birds in the HB-BT group until wk 9 posttreatment (P < 0.05). Similarly, feed waste was generally higher in control birds and least in birds in the HB-BT group (P < 0.05). The IR-BT treatment appeared to be more effective at inhibiting beak regrowth, with a less pronounced effect on feed intake than the HB-BT treatment in laying hen pullets.

Fine structural dependence of ultraviolet reflections in the King Penguin beak horn.

The visual perception of many birds extends into the near-ultraviolet (UV) spectrum and ultraviolet is used by some to communicate. The beak horn of the King Penguin (Aptenodytes patagonicus) intensely reflects in the ultraviolet and this appears to be implicated in partner choice. In a preliminary study, we recently demonstrated that this ultraviolet reflectance has a structural basis, resulting from crystal-like photonic structures, capable of reflecting in the near-UV. The present study attempted to define the origin of the photonic elements that produce the UV reflectance and to better understand how the UV signal is optimized by their fine structure. Using light and electron microscopic analysis combined with new spectrophotometric data, we describe here in detail the fine structure of the entire King Penguin beak horn in addition to that of its photonic crystals. The data obtained reveal a one-dimensional structural periodicity within this tissue and demonstrate a direct relationship between its fine structure and its function. In addition, they suggest how the photonic structures are produced and how they are stabilized. The measured lattice dimensions of the photonic crystals, together with morphological data on its composition, permit predictions of the wavelength of reflected light. These correlate well with experimentally observed values. The way the UV signal is optimized by the fine structure of the beak tissue is discussed with regard to its putative biological role.

Ultraviolet reflecting photonic microstructures in the King Penguin beak.

King and emperor penguins (Aptenodytes patagonicus and Aptenodytes forsteri) are the only species of marine birds so far known to reflect ultraviolet (UV) light from their beaks. Unlike humans, most birds perceive UV light and several species communicate using the near UV spectrum. Indeed, UV reflectance in addition to the colour of songbird feathers has been recognized as an important signal when choosing a mate. The king penguin is endowed with several highly coloured ornaments, notably its beak horn and breast and auricular plumage, but only its beak reflects UV, a property considered to influence its sexual attraction. Because no avian UV-reflecting pigments have yet been identified, the origin of such reflections is probably structural. In an attempt to identify the structures that give rise to UV reflectance, we combined reflectance spectrophotometry and morphological analysis by both light and electron microscopy, after experimental removal of surface layers of the beak horn. Here, we characterize for the first time a multilayer reflector photonic microstructure that produces the UV reflections in the king penguin beak.

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.