Laying hen behavior 2. Cage type preference and heterophil to lymphocyte ratios

The effect of methionine and folic acid administered in ovo on the blood biochemical parameters of chickens (Gallus gallus domesticus)

Methionine is one of the most frequently supplemented amino acids in raising of poultry. However, an overdose of methionine can cause hyperhomocysteinemia. Folic acid, taking part in the process of homocysteine remethylation, is a factor affecting the reduction of the concentration of this amino acid. The study was carried out in 2 stages. The experiment of step I was to investigate the effect of methionine and/or folic acid administration in ovo in the early stage of embryogenesis (E4), and the experiment of the second stage - in the late stage of embryogenesis (E17) on the following biochemical parameters of chicken blood: glucose concentration in whole blood and concentration of homocysteine and uric acid in plasma of domestic chickens (Gallus gallus domesticus). Our results confirm that methionine supplementation may increase the concentration of uric acid and homocysteine. Moreover, we demonstrated that folic acid administered during embryogenesis decreased homocysteine concentration, also in groups simultaneously supplemented with methionine, especially in the initial stage of postnatal life of the bird.

Effects of eggshell temperature pattern during incubation on primary immune organ development and broiler immune response in later life

Eggshell temperature (EST) during incubation greatly affects embryo development, chick quality at hatch, and subsequently various broiler physiological systems. Until now, a constant EST of 37.8°C seems optimal. Data on effects of EST patterns on immune organ development and subsequent broiler immune response are, however, scarce. A higher EST of 38.9°C in week 2 and/or a lower EST of 36.7°C in week 3 of incubation potentially positively affect embryo immune organ development and broiler immune response post hatch. Broiler eggs (n = 468) were incubated at 4 different EST patterns (n = 117 eggs/treatment) from week 2 of incubation onward. Week 1 (embryonic age (E)0 < E7) EST was 37.8°C for all eggs. Week 2 (E7 < E14) EST was either 37.8°C (Control) or 38.9°C (Higher), and week 3 (E14 - /hatch) EST was either Control or 36.7°C (Lower). At hatch, histology of bursal follicles and jejunum villi and crypts were determined as well as heterophil to lymphocyte ratio (H:L) (n = 49). Posthatch, both sexes were grown in 8 pens/treatment for 6 wk (n = 320). Natural antibodies (NAb) were determined at day 14, 22, and slaughter (day 41 or 42) as an indicator of immunocompetence and response to a Newcastle disease (NCD) vaccination was determined by antibody levels at day 22 and slaughter (n = 128). Results showed no interaction EST week 2 × EST week 3, except for jejunum histology. Higher EST in week 2 resulted in lower cell density within bursal follicles (P = 0.02) and a tendency for lower H:L (P = 0.07) at hatch, and higher NCD titers at slaughter (P = 0.02) than Control EST. Lower EST in week 3 resulted at hatch in higher cell density within bursal follicles, higher H:L (both P < 0.05), and a tendency for a higher posthatch mortality rate than control EST (P = 0.10). In conclusion, higher EST in week 2 during incubation may benefit embryonic immune organ development and posthatch broiler immunocompetence, while lower EST in week 3 showed opposite indications.

Evaluation of copper nanoparticles and copper sulfate effect on immune status, behavior, and productive performance of broilers

Objective:

This study was conducted to compare between the nanoparticles of copper (Cu-NP) and copper sulfate (CuSO₄) effect on immunity, pro-inflammatory cytokine, oxidant/antioxidant balance, different behavioral patterns, growth rate, and weight gain by adding them in drinking water of broilers.

Materials and Methods:

One hundred and fifty broiler chicks of 1-day-old were randomly divided into three groups: the first group was the control, the second group received CuSO₄ in drinking water (10 mg/l), and the third group received Cu-NP in drinking water (10 mg/l) with replicates (n = 25) for 5 weeks of age. Blood samples collected for estimating immunoglobulins (A, G, and M), superoxide dismutase, pro-inflammatory (IL-6), erythrocyte sedimentation rate, heterophil/lymphocyte (H/L) ratio, malondialdehyde (MDA), corticosterone hormone, and lymphoid organs index weight. Moreover, behavioral observations were undertaken from the 2nd week until the 5th week of age for measuring different behavioral patterns (feeding, drinking, crouching, body care, and comfort behaviors). Chicks were individually weighed weekly (gm); also, the weight gain, the intake of food, and the ratio of feed conversion were calculated.

Results:

Cu-NP administration has improved the blood profile, lymphoid organs index weight in Cu-NP treated broilers in relation to control and CuSO₄ treated groups. Conversely, erythrocyte sedimentation rate, H/L ratio, MDA, and corticosterone hormone were reduced by Cu-NP treatment. Moreover, Cu-NP has a positive effect on all behavioral patterns more than other groups which significantly reflect on the weight of the body, gaining of weight, and the intake of food in the Cu-NP treated group of birds.

Conclusion:

The findings in this study stated that when the drinking water of broilers was supplemented with Cu-NP, there might be an improvement in the immunity, behavior, and productive performance more efficiently than CuSO₄.

H/L ratio as a measurement of stress in laying hens - methodology and reliability

Measuring the ratio of heterophils and lymphocytes (H/L) in response to different stressors is a standard tool for assessing long-term stress in laying hens but detailed information on the reliability of measurements, measurement techniques and methods, and absolute cell counts is often lacking. Laying hens offered different sites of the nest boxes at different ages were compared in a two-treatment crossover experiment to provide detailed information on the procedure for measuring and the difficulties in the interpretation of H/L ratios in commercial conditions. H/L ratios were pen-specific and depended on the age and aviary system. There was no effect for the position of the nest. Heterophiles and lymphocytes were not correlated within individuals. Absolute cell counts differed in the number of heterophiles and lymphocytes and H/L ratios, whereas absolute leucocyte counts between individuals were similar. The reliability of the method using relative cell counts was good, yielding a correlation coefficient between double counts of r > 0.9. It was concluded that population-based reference values may not be sensitive enough to detect individual stress reactions and that the H/L ratio as an indicator of stress under commercial conditions may not be useful because of confounding factors and that other, non-invasive, measurements should be adopted.

Immune-related effects from predation risk in Neotropical blue-black grassquits (Volatinia jacarina)

Predation is a major force shaping natural history traits of birds because of their vulnerability during nesting and higher visibility during diurnal activities. For most birds in the Neotropics, predation is the major cause of nest failure due to the region's high diversity and abundance of predators. The blue-black grassquit (Volatinia jacarina), similarly to other small passerines in the savanna region of central Brazil, suffers extremely high rates of nest predation. Additionally, males may be particularly vulnerable to predators since they are very conspicuous when executing courtship displays. We assessed some of the non-lethal costs of predation risk on this species by comparing physiological and morphological parameters of birds exposed to predator vocalizations with that of control subjects exposed to non-predator vocalizations. Birds exposed to the predator vocalizations exhibited an immune-related reaction (changes in their H/L ratio), but no changes were observed in other biological parameters measured. This article is part of a Special Issue entitled: Neotropical Behaviour.

Invasive and noninvasive measurement of stress in laying hens kept in conventional cages and in floor pens

Measurements of the heterophil:lymphocyte (H/L) ratio (invasive technique) and corticosterone in yolk and albumen (noninvasive techniques) were used to measure stress in 3 commercial laying strains, Lohmann White (LW), H&N White (HN), Lohmann Brown (LB), and a noncommercial cross (CR) between Rhode Island Red (male) and Barred Plymouth Rock (female), kept in conventional cages or floor pens. All chicks were reared in their respective environments, and 450 and 432 pullets were placed at 18 and 7 wk of age in cages and floor pens, respectively. Blood from 12 hens per strain was taken at 19, 35, and 45 wk of age in each housing system. A total of 100 heterophils and lymphocytes were counted and their ratio (H/L ratio) was calculated. Corticosterone was measured in yolk and albumen from 12 hens per strain in each housing system at 22 and 45 wk of age. The H/L ratio was within the normal range. The interaction between environment and strain for the H/L ratio showed that in both environments, LB and CR hens had a higher H/L ratio than LW and HN layers. In cages, there were significant differences in H/L ratios between LW and HN hens that were likely due to genetic differences. The LW hens had significantly lower corticosterone concentrations in yolk than LB hens. In cages but not floor pens, yolk corticosterone concentrations at wk 22 were significantly higher than at wk 45. In floor pens but not cages, albumen corticosterone at wk 22 was higher than at wk 45. The H/L ratios suggest that none of the hens were unduly stressed, and corticosterone levels in yolk and albumen support the suggestion that hens adapted to their environments with age. Although measurement of yolk corticosterone and the H/L ratio may be comparable, the measurement of corticosterone level in the albumen may differ because it is secreted over a short time.