Early egg production in genetically blind (rc/rc) chickens in comparison with sighted (Rc+/rc) controls

How does visible light flicker impact laying hen pullet behavior, fear, and stress levels?

Many characteristics of artificial light have been evaluated; however, light-flicker frequency (F) has not been assessed extensively in poultry. Pullets (1,344 per strain [S]; Lohmann Brown-Lite [LB] and LSL-Lite [LW]) were placed into 8 light-tight rooms, containing 6 floor pens (15 pen replicates per F × S for 30 and 250 Hz; 18 pen replicates per F x S for 90 Hz), and assigned 1 of 3 F treatments (30, 90, 250 Hz). The experiment took place over 2 trials (blocks). To evaluate long-term effects of F during rearing, birds were followed through the hen phase. Data were analyzed using Proc Mixed (SAS 9.4). Differences were considered significant when P ≤ 0.05, and behaviors are expressed as percentage of time. Pullets reared under 30 Hz spent more time performing nutritive behaviors (P < 0.01) and as "unidentified" (P = 0.02) than other treatments. Active behavior demonstrated an age x F interaction, with pullets being more active at 16 wk, regardless of F (P < 0.01). Comfort behaviors were higher at 16 wk compared to other ages, regardless of F (P < 0.01). Exploratory behaviors were lowest at 4 wk in pullets under 30 Hz (P < 0.01). Aggressive behaviors (12 wk) were higher in pullets reared under 250 Hz than those under 90 Hz (P < 0.01). Comb score was unaffected by F (P = 0.79) and all birds scored had a full plumage. Heterophil-to-lymphocyte ratio was unaffected by F at 7 or 15 wk (P = 0.85 and P = 0.54, respectively). In trial 1, pullets reared under 90 Hz had higher corticosterone concentrations than those reared under 250 Hz (P = 0.02) and trial 2 there were no effects of F (P = 0.97). For novel object test, LW pullets reared under 90 Hz had a higher latency to peck than LW pullets under 30 Hz or 250 Hz (P = 0.03). Hen behavior (wk 39) and fear tests (36 wk; novel object test (P = 0.86) and tonic immobility (P = 0.37)) were unaffected by F. Overall, minimal effects of F were seen on pullet and hen behavior and stress.

Dietary supplementation with β-mannanase and probiotics as a strategy to improve laying hen's welfare

A trend toward animal welfare improvement is observed in animal production, in addition to restrictions imposed on the use of antimicrobials. This study's objective was to evaluate whether β-mannanase and probiotic supplementation can change hen's behavior. Light weight laying hens (36 weeks old) were housed in cages randomly allocated to one of four different treatments: control group, fed non-supplemented diets; diets supplemented with 300 g/ton of β-mannanase; diets supplemented with 50 g/ton of probiotic; or diets containing both 300 g/ton of β-mannanase and 50 g/ton of probiotic. The behavior of 24 birds was recorded for a week using video cameras. The frequency and time of main behaviors (eating, walking, standing, sitting, drinking, and exploring) were analyzed in three periods per day (from 09:00 to 09:15; from 01:00 to 01:15, and from 04:00 to 04:15), as well as the time of other behaviors (leg-stretching and wings, scratching, wing-flapping, aggressive and non-aggressive pecks). Frequency and lesion scores were also analyzed using a visual score of three body regions: neck, tail, and cloaca; as well as comb injuries. β-mannanase was able to increase the frequency of feeding behavior by 49% (P < 0.05) and hens also spend 20% (P < 0.05) more time in this behavior compared to the control treatment. The use of probiotics also enhanced by 39% (P < 0.05) the frequency and 19% the time (P < 0.05) and the supplementation with combined additives was able to increase by 29% (P < 0.05) the frequency and 25% (P < 0.05) the time in feeding behavior. β-mannanase and probiotics also increased the frequency and time spent exploring behavior (P < 0.05) and promoted a higher frequency in standing behavior (P < 0.05) and decreased the time spent on sitting behaviors (P < 0.05). The combined additives showed less frequency and time in sitting behaviors (P < 0.05), while increased wing-flapping behavior (P < 0.05). All the treatments were able to reduce pecking (P < 0.05). Therefore, the addition of β-mannanase and probiotics to laying hen diets is an effective strategy to improve bird welfare.

Genome-wide transcriptome and physiological analyses provide new insights into peanut drought response mechanisms

Drought is one of the main constraints in peanut production in West Texas and eastern New Mexico regions due to the depletion of groundwater. A multi-seasonal phenotypic analysis of 10 peanut genotypes revealed C76-16 (C-76) and Valencia-C (Val-C) as the best and poor performers under deficit irrigation (DI) in West Texas, respectively. In order to decipher transcriptome changes under DI, RNA-seq was performed in C-76 and Val-C. Approximately 369 million raw reads were generated from 12 different libraries of two genotypes subjected to fully irrigated (FI) and DI conditions, of which ~329 million (90.2%) filtered reads were mapped to the diploid ancestors of peanut. The transcriptome analysis detected 4,508 differentially expressed genes (DEGs), 1554 genes encoding transcription factors (TFs) and a total of 514 single nucleotide polymorphisms (SNPs) among the identified DEGs. The comparative analysis between the two genotypes revealed higher and integral tolerance in C-76 through activation of key genes involved in ABA and sucrose metabolic pathways. Interestingly, one SNP from the gene coding F-box protein (Araip.3WN1Q) and another SNP from gene coding for the lipid transfer protein (Aradu.03ENG) showed polymorphism in selected contrasting genotypes. These SNPs after further validation may be useful for performing early generation selection for selecting drought-responsive genotypes.

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.

Dietary Inositol Reduces Fearfulness and Avoidance in Laying Hens

Simple Summary

Brain inositol is known to affect memory, and the incidence of depression, anxiety, and obsessive-compulsive disorder in mammals. Phytate, a naturally occurring inositol ester in plants, binds other nutrients, making them unavailable for digestion. The addition of phytase, the enzyme capable of hydrolyzing phytate, to diets increases the release of both inositol and nutrients for absorption in the chicken digestive tract. In this study, we assessed how dietary phytase or pure inositol affected laying hen behaviour, fearfulness, aggression, and stress levels. To increase the probability of seeing effects, hens were not beak treated and were fed two balanced protein levels differing in digestible amino acid sufficiency. Inositol did not affect stress levels, as measured by heterophil-to-lymphocyte ratio, or the number of hen comb or skin lesions. However, regardless of the source, pure inositol or phytase derived inositol reduced the number of feathers in the vent area, suggesting an increase in feather pecking. Pure inositol reduced fearfulness in laying hens, but phytase-derived inositol did not.

Abstract

Myo-inositol (inositol) affects memory, and the incidence of depression and anxiety in mammals. An experiment was designed to determine if pure inositol (0.16%), or high levels of phytase (3000 FTU/kg) affect the behaviour of fully beaked Lohmann LSL lite hens fed amino acid sufficient (19% crude protein (CP)) and deficient diets (16% CP), from 19 to 59 weeks of age. The data collected included live-scan behaviour observations and novel object (NO) tests (both at 1, 10 and 40 weeks of the trial); heterophil-to-lymphocyte (H/L) ratios (week 1 and week 40 of the trial); end of trial feather cover, and comb and skin lesions; and daily mortality. Reducing CP increased sitting by 2.5%. Inositol, but not phytase, reduced the latency to peck at the NO by 300 sec. Inositol reduced vent feather cover by 12% and tended to increase mortality by 13%. No effects on H/L ratio, and comb or skin lesions were found. In conclusion, regardless of the source, inositol reduced vent feather cover, while it tended to increase mortality. Only pure inositol reduced fearfulness in laying hens.

The influence of environmental enrichment and stocking density on the plumage and health conditions of laying hen pullets

In this study, the effects of environmental enrichment, stocking density, and microclimate on feather condition, skin injuries, and other health parameters were investigated. During 2 rearing periods (RP), non-beak-trimmed Lohmann Brown hybrid pullets were housed in an aviary system for rearing with cages and from week 5 of age onwards with access to a litter area. All pullets were reared in the same barn and under practical conditions. In total, 9,187 (RP 1) and 9,090 (RP 2) pullets were distributed in 9 units, and each unit was assigned to 1 of 3 experimental groups (EG). In the control group (EG 1), the pullets were kept without environmental enrichment and at a commonly used stocking density (22 to 23 pullets per m²). Each unit of the 2 treatment groups was provided with 3 types of environmental enrichment simultaneously (pecking stones, pecking blocks, and lucerne bales), and the pullets were kept at a lower than usual (18 pullets per m²) (EG 2) or commonly used stocking density (EG 3). In each RP, the plumage condition, injuries and health of the pullets, and the microclimate of the housing system were examined 5 times. The statistical relationships of enrichment, stocking density, and microclimate with animal health were estimated via regression models. We found that the provision of environmental enrichment had a significant increasing effect on the plumage quality in week 17. Furthermore, significant relationships were found between several predictors (temperature in the housing system, dust concentration, and age of the pullets) and response variables (plumage condition, body injuries, head injuries, bodyweight, difference to the target weight and uniformity). The results of this study showed that increasing temperature in the housing system and increasing age of the pullets are significantly associated with the occurrence of feather damage and skin injuries during rearing. With stocking densities as high as we used (all > 17 pullets per m²), no significant positive effect of a reduced stocking density could be observed.

Is There a Need for a More Expansive Use of Ethics and Values in Reflecting on the Use of Animals in Scientific Research?

Simple Summary

Debates about animal research are often polarized. On one side, increased knowledge, medical treatments or enhanced animal production are seen to justify harms. On the other, animals have rights constraining their use. Both sides fail to provide adequate support for this contentious use of animals. Reflecting the richness of ethics, it is suggested that empathy and respect for the animal, and greater acknowledgement of the value of experiences and care could also be considered. Along with a more informed understanding of the benefits of research and of the aims of animal rights, a more sophisticated ethic may reflect the common ground between the poles of the debate.

Abstract

Although reflecting a long tradition of moral reflection that the use of animals is acceptable as long as it is humane, the tension between causing harm to animals in research and the benefits to humans can nevertheless be troubling. Utilitarian arguments that appeal to the value of those practices in sustaining and enhancing human lives, and rights-based arguments which seek to constrain them, can be inadequate. Reflecting a more engaging, inclusive and sophisticated understanding of human activity, justification for animal use could be expanded to reflect the fullness and richness of ethical thinking. This might see more explicit inclusion of perspectives borne of virtues, caring, experiences, and respect for the essence of the animal, and different ways of understanding and knowing animals, values drawn from the middle ground of commonly acceptable human-animal relationships. Such values, already clearly evident in research, could be more widely integrated into arguments justifying animal use. A more expansive approach would not only reflect reality and acknowledge that costs and benefits are shared more widely, but it might result in more equitable, effective and humane science. It might also serve to reduce some of the tension long evident in the relationship between humans and animals.

Human capabilities, mild autism, deafness and the morality of embryo selection

A preimplantation genetic test to discriminate between severe and mild autism spectrum disorder might be developed in the foreseeable future. Recently, the philosophers Julian Savulescu and Guy Kahane claimed that there are strong reasons for prospective parents to make use of such a test to prevent the birth of children who are disposed to autism or Asperger's disorder. In this paper we will criticize this claim. We will discuss the morality of selection for mild autism in embryo selection in a hypothetical in vitro fertilization (IVF) situation where preimplantation genetic diagnosis is performed and compare this with a similar selection for congenital deafness. To do this we first discuss relevant human differences. We then introduce the principle of human capabilities (PC) and compare this principle with the principle of procreative beneficence (PB) introduced by Savulescu and Kahane. We apply the two principles to selection for mild autism and selection for congenital deafness. We argue that PC allows for the selection for mild autism but rules out selection for congenital deafness. PB will not give clear answers; the ruling of PB depends to a large extent on expected social, cultural and political developments. We will argue that PC is preferable to PB. We will discuss arguments for the value of mild autism for individuals who have this condition and argue that they are able to lead a life with human dignity provided autism-friendly social circumstances are present. Neither PC nor PB yields strong reasons for prospective parents to seek to prevent the birth of children who are disposed to mild autism spectrum disorder.

After Dolly—Ethical limits to the use of biotechnology on farm animals

The cloning of Dolly the sheep gave rise to a widespread call for limits on interference with life. Until recently, the main limits were technical: what it is possible to do. Now scientists are faced with ethical limits as well: what it is acceptable to do. In this context, we take ethics to involve systematic and rational reflection on moral issues raised in the public sphere. The concerns of the general public are not necessarily valid, but they are the best point of departure if the discussion is to lead to a socially robust framework for setting limits to the use of animal biotechnology. To assess public understanding, we examine two sources of data: Eurobarometer surveys from 1991 to 2002 and a qualitative interview study carried out in Denmark in 2000. Based on these sources, we formulate, and then discuss closely, the following concerns: dangers to human health and the environment, animal welfare, animal integrity, and usefulness. In the final part of the article, it is proposed that a principle of proportionality should be the foundation for socially robust applications of animal biotechnology. Only in cases where the usefulness of the technology can be said to outweigh countervailing moral concerns, as in biomedical research, will applications of animal biotechnology stand up to scrutiny in the public sphere.

Changes in light intensity can influence age at sexual maturity in domestic pullets

1. Shaver White and ISA Brown pullets were reared to 140 d in groups of 8 in cages on a 10-h photoperiod of incandescent light and maintained at an illuminance of 3 or 25 lux, or transferred from 3 to 25 lux or from 25 to 3 lux at 63 or 112 d of age. 2. There was no significant difference in sexual maturity, measured as eggs per 100 bird.d at 139 and 140 d, for ISA Brown maintained on 3 or 25 lux, but Shaver White pullets exposed to constant 3 lux matured significantly later than those maintained on 25 lux. 3. In Shaver Whites, sexual maturity was significantly delayed by an increase from 3 to 25 lux at 63 and 112 d, and advanced by a decrease from 25 to 3 lux at 112 d. Sexual maturity of ISA Browns was not significantly affected by a change in illuminance at 63 or 112 d, though responses were in the same direction as for Shaver Whites. 4. In both breeds, total feed consumed to 112 d was higher for birds on 3 lux than 25 lux, but lower between 112 d and 140 d when birds on 25 lux underwent rapid sexual development. In both breeds, body weight at 63 d was higher for birds exposed to 3 lux than 25 lux, but body weight gain thereafter was similar for the two light intensities. 5. In both breeds, plasma luteinising hormone (LH) concentration at 63 and 112 d was lower in birds maintained on 3 lux than 25 lux. At 63 and 112 d, transfers from 25 to 3 lux depressed, whereas transfers from 3 to 25 lux at 63 d, but not at 112 d, increased plasma LH. 6. Advances or delays in sexual maturity induced by changes in illuminance were not correlated with differences in feed intake, body weight gain, or with changes in plasma LH. 7. One possible explanation for the inverse relationship between the direction of change in illuminance at 63 and 112 d in pullets exposed to a 10-h photoperiod and the age at which they became sexually mature is that changes in light intensity and/or spectral composition affect the entrainment of the circadian rhythm of photoinducibility, to effect a phase shift in the photoinducible phase and/or the responsiveness of phototransduction pathways.

Staying Good While Playing God - The Ethics of Breeding Farm Animals

Modern genetics has given us some very efficient tools with which to alter the characteristics of animals. To date, farm animal breeders have mainly used these tools to increase productivity. Thus, each new generation of farm animals matures faster, yields more milk, or produces more meat or eggs, than the previous one. Despite these apparent benefits, modern farm animal breeding has had severe negative consequences, including effects on the quality of the animals’ lives and biodiversity. The aim of this paper is to discuss the goals and consequences of farm animal breeding within an ethical context. First, a description of what has happened to broilers and dairy cattle as breeders have pursued the goal of ever more efficient production is given. Second, the ethical values that ought to underlie future breeding schemes are discussed. It is suggested that there are in fact two very different ethical approaches: the ‘quality of life-based ‘ approach and the ‘preservationist ‘ approach. A view combining elements from both approaches is advanced. Finally, an example is given of how it is possible, in practice, to pursue an ethically defensible breeding goal without compromising production efficiency.

Effects of sex-linked imperfect albinism in the chicken (sal-c) on plasma luteinising hormone concentrations and early egg production

1. When measured before and after the onset of darkness, plasma LH concentrations in 40-day-old sex-linked albino pullets (sal-c) were slightly lower than those of nonalbinos (s+). 2. This finding prompted an experiment in which plasma LH concentrations were measured between 12 and 33 weeks of age when daylength was increased at 15 or 21 weeks. Egg production of the early and late maturing albino hens was measured. 3. Plasma LH concentrations overall and at 17 weeks were lower for albinos than for nonalbinos. In the early maturing group egg production of albinos was higher than that of nonalbinos. 4. Results suggest that increased egg production of albinos is not the direct result differences in plasma LH concentrations but may be a consequence of differences in the control of LH secretion.

Effects of light on melatonin and two enzymes leading to its production in albino (s(al-c)) and nonalbino chickens

A gene for sex-linked imperfect albinism in the chicken (s(al)) has been associated with increased egg production with an implication that environmental light may play a role. In this study, levels of melatonin and hydroxyindole O-methyltransferase (HIOMT) and N-acetyltransferase (NAT), two enzymes leading to melatonin production, were studied in young albino and nonalbino chickens in relation to the daily light cycle, and after 19 days of constant light or dark. Differences between genotypes were found in the levels of HIOMT activity in the pineals and retinas of birds kept in constant light for 19 days. Other measurements were not significantly different. This study would appear to show that the visual system of imperfect albino chickens reacts differently to light than that of nonalbinos, but not with changes in the daily cycle of plasma melatonin or in NAT activity, which is the enzyme primarily responsible for the control of the melatonin level in the body.

Inherited changes in concentrations of retinal and serum melatonin in the chicken

Concentrations of melatonin in the retina, serum, and pineal gland were studied in genetically blind chicks carrying an autosomal recessive mutation, rc, characterized by the degeneration of photoreceptors in the retina after hatching. Blind homozygous (rc/rc) and sighted heterozygous (Rc+/rc) chicks were housed under 12:12 light:dark cycles. They were decapitated at 4, 6, 8, and 10 weeks of age at midlight and middark. Retinas, pineal glands, and serum samples were collected, and the resultant tissue melatonin was extracted and determined by radioimmunoassay. Retinal and pineal melatonin were also identified and quantified by gas chromatography-mass spectrometry (GC-MS). Good correlations were demonstrated between the values obtained by GC-MS and levels of quantified by radioimmunoassay. In all the tissues studied, there were age-related changes and diurnal variations in melatonin levels with high levels in the dark period. Melatonin levels in the retina and serum of rc/rc chicks were also significantly lower than those of Rc+/rc control birds. However, storages of melatonin in the pineal gland were similar between the two groups of chicks studied. These results suggest that (1) retinal melatonin is synthesized in the photoreceptor, (2) the phototransduction process which produces neural signals (i.e., electroretinogram) may be different from the phototransduction process which initiated the rhythmic melatonin synthesis and production in the retina, (3) the inherited degeneration of retinal photoreceptors with lower retinal melatonin levels correlates with an inherited abnormality of the pineal melatonin synthesis and/or secretion resulting in lower serum melatonin levels (pleiotropism), (4) levels of pineal melatonin (an indicator of the rate of synthesis and/or storage) and that of serum melatonin (an indicator of the rate of release) may not be directly correlated, and (5) the chicken pineal secretes melatonin not only by simple diffusion but also from a bound pool of melatonin in the gland.

Physical activity and energy expenditure of laying hens as affected by light intensity

The influence of light intensity using incandescent bulbs in a 16L:8D day:night schedule on the number and strength of movements and on total, resting and activity-related energy expenditure was investigated. Movements were classified into 10 activity levels of progressively increasing vigour. The number of movements at all activity levels was significantly positively correlated with the logarithm of the light intensity. Movements of low activity strength were less affected by increasing light intensities than vigorous movements. Activity-related energy expenditure was highly significant and positively affected by light intensity. A decrease of the light intensity from 120 to 1 lux may reduce total energy expenditure by 18%. A decrease in energy expenditure by 9% may be achieved by reducing the light intensity to about 15 lux, measured perpendicular to the main axis of radiation.