Minimal Effects of Rearing Enrichments on Pullet Behaviour and Welfare.

In Australia, free-range pullets are typically reared indoors, which may hinder later adjustment to outdoor access. Rearing enrichments could optimise pullet development. Hy-Line Brown® chicks (n = 1700) were reared indoors across 16 weeks with 3 enrichment treatments: (1) a standard control; (2) novel objects (novelty) provided weekly or (3) perching structures (structural) provided. All pullets were weighed at 5, 8, 12, and 16 weeks old. Pullets (n = 87) were tested in a novel arena at 9 weeks and manual restraint (n = 90) at 16 weeks. At 15 weeks, lymphoid organs were extracted and weighed from 90 pullets. Pullets were transferred to the free-range facility at 16 weeks and housed in 9 identical pens within rearing treatments. Hens perching were counted via video recordings across the first week. The structural pullets had the highest relative adrenal weights (p = 0.03) but differences may not have been biologically relevant. Structural hens perched less than the novelty hens in the layer facility (p = 0.02). There were no other consistent rearing treatment differences. The rearing environments had minimal effects on pullet behaviour and welfare, but data from the adult hens did show some longer-term welfare impacts.

Rearing Enrichments Affected Ranging Behavior in Free-Range Laying Hens.

Within Australia, free-range systems are prevalent, but pullets destined for range access are reared indoors. This mismatch between rearing and layer housing may hinder adaptation to the free-range environment. Rearing enrichments could enhance pullet development. A total of 1,386 Hy-Line Brown® chicks were reared inside an experimental facility across 16 weeks with 3 enrichment treatments including (1) a control group with standard floor-housing, (2) a novelty group providing novel objects that changed weekly ("novelty" hens), and (3) a structural group with custom-designed H-shaped structures including opaque sides ("structural" hens). At 16 weeks of age, all pullets were leg-banded with microchips and moved to an experimental free-range system with 9 identical pens (n = 3/rearing treatment). From 25 to 64 weeks, individual hen daily ranging behavior was tracked via radio-frequency identification technology and grouped into 6 age periods per rearing treatment. Video footage was used to count the number of hens at different distances on the range for the first 14 days of access, and eggs were assessed for albumen corticosterone concentrations 4 days prior to (n = 450) and 1 week after first range access (n = 450). Across most age periods, the structural hens spent the most time ranging (P ≤ 0.01), the novelty hens showed the fewest number of visits to the range (P < 0.0001), and both enriched hen groups had the longest maximum visit durations (P ≤ 0.02). Range use increased with age across all treatments with only 3% of hens never going outside. All hens were initially slow to use the range area with fewer novelty hens venturing farther onto the range (P ≤ 0.03). The structural hens had higher albumen corticosterone concentrations and variance (both P ≤ 0.004) prior to range access. All hens showed an increase in albumen corticosterone following the first week of range access resulting in no differences between rearing treatments in means (P = 0.92) and variance (P = 0.63). Different enrichments have differing impacts on ranging behavior, but further research is needed to understand the mechanisms of effects, with differences in brain lateralization a potential hypothesis to be tested.

Relationships Between Rearing Enrichments, Range Use, and an Environmental Stressor for Free-Range Laying Hen Welfare.

Enrichments during pullet rearing may improve adaptation and welfare of hens as they move from indoor rearing to a free-range system. Individual variation in outdoor ranging may also affect welfare. This study assessed the effects of rearing enrichments and an imposed environmental stressor on hen welfare and egg quality along with the association of welfare with ranging. Hy-Line Brown® chicks (n = 1,386) were reared indoors until 16 weeks with 3 enrichment treatments including a "control" group with standard floor litter, a "novelty" group that received novel objects that were changed weekly, and a "structural" group with H-shaped perching structures. Pullets were then moved to a free-range system with three replicates of each rearing treatment. Daily ranging was individually tracked from 25 to 64 weeks via radiofrequency identification technology. Individual hen welfare assessments were performed at 25, 33, 43, 56, and 64 weeks and correlated with ranging time prior to these dates. At 44 weeks, the range area was reduced by 80% for 11 days to induce stress. Changes in ranging behavior, albumen corticosterone concentrations and egg quality were evaluated. GLMMs showed significant interactions between hen age and rearing treatment for live weight, number of comb wounds, plumage coverage, and toenail length (all P ≤ 0.003), with the enriched hens showing more consistent live weight at the later ages, fewer comb wounds at 33 weeks, and better plumage coverage at the later ages, whereas the structural hens had shorter toenails as age increased. Plumage coverage showed a positive relationship with range use across most age points (P < 0.0001). Hens reduced ranging time following the imposed stressor but increased their number of visits with the lowest increase by the structural hens (P = 0.03). Significant interactions between rearing treatment and stressor for albumen corticosterone concentrations showed the structural hens decreased concentrations immediately post-stress, but the control and novelty groups increased (P < 0.006). The stressor increased or decreased values of most egg quality parameters across all rearing groups (all P ≤ 0.02). Overall, provision of rearing enrichments and greater range use may have positive impacts on hen welfare.

Metabolic fate of intravenously administered N-acetylneuraminic acid-6-14C in newborn piglets.

BACKGROUND: Sialic acid (N-acetylneuraminic acid), a component of gangliosides and sialylglycoproteins, may be a conditional nutrient in early life because endogenous synthesis is limited. The aim of this study was to investigate the metabolic fate of intravenously administrated N-acetylneuraminic acid-6-14C (sialic acid) in piglets. METHOD: Three-day-old male domestic piglets (Sus scrofa) were injected via the jugular vein with 5 microCi (11-12 x 10(6) cpm) of N-acetylneuraminic acid-6-14C (specific activity of 55 mCi/mmol). Blood samples were collected at regular intervals over the next 120 min. The organs were then removed and the urine collected for determination of residual radioactivity. RESULTS: Within 2 min of injection, 80% of the activity was removed from the blood and by 120 min the remaining activity approached 8%. At 120 min, the brain contained significantly more radioactivity (cpm/g tissue) than the liver, pancreas, heart and spleen, but less than the kidneys. Within the brain, the percentage of total injected activity was highest in the cerebrum (0.175 +/-0.008) followed by the cerebellum (0.0295 +/-0.006, p=0.00006) and the thalamus (0.029 +/- 0.006, p =0.00003). CONCLUSIONS: An exogenous source of sialic acid is capable of crossing the blood-brain barrier and being taken up into various tissues. The findings suggest that dietary sources of sialic acid may contribute to early brain development in newborn mammals.

A review of the effects of supplementary nutrition in the ewe on the concentrations of reproductive and metabolic hormones and the mechanisms that regulate folliculogenesis and ovulation rate.

This paper discusses the phenomenon of nutritional flushing in ewes whereby increased nutrition stimulates folliculogenesis and ovulation rate. In addition the paper reviews recent findings on the effects of increased levels of nutrition on the blood concentrations of reproductive and metabolic hormones in the ewe and some of the intraovarian changes that take place in response to nutritional stimulation. Finally, in the paper, we propose a model of the physiological mechanism for the nutritional stimulation of folliculogenesis and we review how closely the model fits recent published and unpublished evidence examining the mechanism of flushing. Nutritional stimulation alters the blood concentrations of some metabolic hormones. By using short-term models of nutritional flushing, we have shown that as the blood concentrations of insulin and leptin increase that of growth hormone decreases while that of IGF-I appears unaffected by the nutritional flushing. Nutritional flushing also alters the blood concentrations of some reproductive hormones. Again, using the same model, we have shown that there is a transient increase in FSH and a decrease in oestradiol concentrations in the blood. The changes in oestradiol are particularly evident in the follicular phase of the oestrous cycle. In the ovary, the effect of nutrition is to stimulate folliculogenesis. These changes are associated with intra-follicular alterations in the insulin-glucose, IGF and leptin metabolic systems. The stimulation of these intra-follicular systems leads to a suppression in follicular oestradiol production. The consequence of these direct actions on the follicle is a reduced negative feedback to the hypothalamic-pituitary system and increased FSH secretion that leads to a stimulation of folliculogenesis.