The 2009 Poultry Science Association Meeting included a number of presentations which have direct implications for commercial egg production. The significant papers are reviewed within topic categories.
Welfare
Welfare is a significant issue relating to the design of housing, production management and consumer acceptance. Presentations at the PSA Meeting encompassed rearing, colony vs. conventional cages and nutrient composition in eggs from hens housed in cages compared to range production.
Article 170 – A Comparative Examination of Rearing Parameters for Brown Egg-Type Pullets Grown for Either Range or Cage Production
This presentation is derived from data assembled from the random sample test conducted by Ken Anderson at North Carolina State University. His studies have recently been extended to floor-housed flocks in both cage-free houses and on pasture. Hy-Line brown pullets were reared using either cages allowing 48 inch2 per pullet or brooded in floor pens allowing 1 ft2/pullet with transfer to range at 12 weeks of age. Pullets reared in cages were heavier than pen/range reared birds by 0.2 lb. Total feed consumed was 13% lower in pen/range reared pullets attributed to foraging after 12 weeks of age. It was noted that pullets must gain familiarity with ranges, roosts and nests and learn foraging behavior prior to onset of production.
Article 174 – A Comparison of Humoral Immune Function in Response to a Killed Newcastle Vaccine Challenge in Caged vs. Free-Range Hy-Line Brown Layers
In an attempt to evaluate stress in hens subjected to either cage or range housing, subjects were injected with an inactivated Newcastle disease emulsion to compare antibody titers as influenced by housing system. Caged hens demonstrated a significantly higher level of antibody production compared to free-range hens. Heterophilia (increased ratio of heterophil blood cells to lymphocytes) consistent with higher levels of stress was documented. These findings are consistent with the acknowledged higher mortality in free-range hens compared to flocks housed in cages.
Article 246P – Effect of Different Cage-Systems on Laying Hen Welfare
Scientists at the Shandong Agricultural University compared the performance of laying hens in conventional cages with aviaries and furnished cages. Feed conversion ratio was significantly lower in standard tiered cages and egg output was significantly higher than in the alternative non-confined systems. There was no difference in either egg production or feed conversion between aviaries and furnished cages. After experiencing fear, the plasma non-esterified fatty acid levels were significantly lower in caged hens compared to alternative systems. It is significant that the study did not evaluate corticosteroid levels or heterophil ratios which are standard measures of stress. Plasma creatine kinase, uric acid, glucose or non-esterified fatty acids which were determined would not generally be regarded as direct indicators of the level of stress. The authors’ conclusion that there is greater stress in conventional cages cannot be supported by either the experimental design or the data obtained.
Article 225 – Comparison of Nutrient Composition in Eggs from Hens Housed in Cage vs. Range Production Facilities
Dr. Ken Anderson evaluated the validity of the public perception concerning the presumed superior nutrient qualities of range eggs in product derived from the NC Random Sample Test. Egg pools were sent to four laboratories to determine cholesterol, omega-3 fatty acids, saturated fat, beta carotene, Vitamin A and Vitamin E. Total fat content in samples varied from a high of 8.9% to low of 6.8%. Eggs from range production had higher total fat, monounsaturated fat and polyunsaturated fat than eggs produced by caged hens. The omega-3 levels were stated to be 0.17% in range eggs compared to 0.14% in caged eggs. There was no impact on cholesterol with values of 327 and 331 mg/100 g for caged and ranged hens respectively. Neither vitamin A nor vitamin E level was affected by housing system but both treatments showed a decline at 62 weeks of age.
Beak treatment
Article 172 – Effects of Degree of Beak Trimming on the Performance of White Leghorn Hens
The effects of beak treatment on performance of Lohmann LSL and Shaver hens were evaluated by scientist of the University of Saskatchewan.
Treatments included the following:
- Day old infrared beak trim at two intensities,
- Day old hot-blade beak trim using appropriate templates for either Bovans or CV-20 strains. Degree of trim ranged from mild through moderate to severe.
- A non-treated group served as the control
- Pullets were housed in cages through 17 weeks of age and were evaluated during a 40- week production cycle. Hot blade trimming allowed three levels of reduction in beak length (14%, 31% and 39% shorter than controls) when evaluated at 38 weeks of age.
The infrared treatment resulted in beaks that were 30% to 36% shorter than the control. Body weight was reduced for hens subjected to hot blade trimming at the most severe level at both 20 and 38 weeks but the effect was absent at 60 weeks of age. The important observation was that hen-day egg production was not affected by any of the methods of beak trim. In contrast mortality was increased due to cannibalism in the control hens. Feed intake was decreased proportionally to the severity of beak trim but without affecting egg quality parameters.
Article 171 – Effects of Degree of Beak Trimming on the Behavior and Feather Condition of White Leghorn Hens
In a related presentation the Saskatchewan group evaluated behavior as influenced by the methods of beak trimming. Compared with the controls, infrared treatment resulted in object pecking at 3 and 16 weeks. There was a decrease in aggressive behavior and frequency of drinking, and an increase in object pecking irrespective of treatment during the production cycle. Feather condition as evaluated at 38 and 60 weeks of age in hens subjected to any of the beak trimming treatments was superior to controls with entire beaks.
Article 248 – The Effect of Beak Trimming, Bird Density and the Use of Perches on Productivity of Hy-Line W-98 Single Comb White Leg Pullets from 1-16 Week of Age
A study was conducted in Honduras to evaluate the possible interaction of beak trimming and perching. Body weights were not significantly affected by perches at the three levels of stocking density (1.3 ft2/pullet, 1.1 ft2/pullet, 0.9 ft2/pullet). Beak trimming reduced body weight significantly and reduced feed intake. Neither of the treatments nor their interaction influenced mortality, uniformity or the blood heterophil to lymphocyte ratio. There does not appear to be any undesirable effect of beak trimming in floor-reared pullets. This trial did not take into account the beneficial effect of installing perches during rearing on subsequent socialization of the flock which influences aggression, vent peck and failure to deposit eggs in nests, which are all common problems encountered in floor systems.
Safety
In contrast to previous PSA meetings, there were only a few papers dealing with food safety in relation to eggs, most of which represented contributions from the USDA Agriculture Research Service.
Article 173 – Potential for Horizontal Transmission of Salmonella and Campylobacter among Caged and Cage-Free Laying Hens
A trial conducted at the USDA-ARS Russell Research Center involved infecting shedder hens with Salmonella and Campylobacter by both the oral and intra-vaginal routes. These hens were then placed among non-infected susceptible hens in either colony cages, on all-wire slats or litter flooring. Salmonella was recovered from 2 out of 4 ceca of contacts in colony cages. From hens housed on wire slats, Salmonella was recovered from 2 out of 3 ceca and 1 out of 3 spleens from the challenged hens and 2 out of 12 ceca from non-challenged contacts. There was only a slow spread of Campylobacter among hens on wire slats. Campylobacter was recovered from 1 out of 3 ceca of challenged hens and 7 out of 12 ceca of co-mingled contact hens. Salmonella was not recovered from any of the infected or contact hens housed on litter. The results of this trial are difficult to interpret. One possibility is that mature hens with intact intestinal flora resist colonization. It is evident that hens housed on wire slats or in cages which inhibit coprophagy are generally refactory to Campylobacter infection since the organism cannot persist in a dry environment and requires moist fecal material in which to survive. The logical extension of this study would be to evaluate the shedding of SE in hens receiving successive doses of live attenuated SE vaccine as pullets compared to controls
Article 228 – Room Environment Influence on Eggshell Bacterial Levels of Non-Washed and Washed Eggs from Caged and Caged-Free Laying Hens
There is renewed interest in the EU regarding the washing of eggs which is a standard U.S. practice. Eggs were collected from hens housed either on wire slats or from litter pens and were assayed for aerobic bacteria and coliforms. Non-washed eggs produced by hens on litter had higher numbers of bacteria and coliforms compared to eggs produced on slats. Washing significantly reduced total plate count by 1.6 log10 cfu/mL. Washing significantly reduced coliform counts by 0.5 log10 cfu/mL. Housing hens in cages with manure removal belts resulted in the lowest total plate counts for both non-washed and washed eggs compared to housing in a room with cages, slats or shavings. Since all commercial eggs are washed in accordance with USDA directives specifying temperature, chlorine level and pH of sanitizer, shell contamination in U.S. eggs should be low. It is noted that eggs produced on currently available on-belt manure drying systems are generally free of dust, resulting in cleaner eggs than those derived from high-rise houses.
Molting
Although producers conforming to UEP Guidelines now initiate molt using diets of low energy and salt content, there are still aspects of molting which are worthy of scientific evaluation including welfare and dietary formulation.
Article 242P – Molting Hens Using Soy Hulls: 1. Physiological Response
A study conducted in Brazil considered the physiological stress of hens subjected to either feed removal or alternative molting programs. The response of hens was determined by assaying blood plasma, cholesterol, glucose, triglycerides, high and low density lipoproteins at 79 through 92 weeks of age using Hy-Line W-36 hens with induction of molt at 80 weeks of age (most molting in the U.S. commences at 65 weeks). The control comprised 10 days of fasting followed by cracked corn for 8 days and a pullet developer for 10 days. This regimen corresponds closely to previous U.S. practice. Alternative molting diets consisted of soy hulls for 4 to 12 days followed by low energy diets comprising soy hulls for 8 or 12 days, in turn followed by 10, 6, or 2 days of a low energy diet containing soy hulls and then 4 days of cracked corn and 10 days of pullet developer. Molted hens showed lower triglyceride levels than control birds regardless of molting diet. No differences were observed among treatments with respect to plasma assays. Data was not provided on subsequent performance of hens molted using alternative programs,
Article 234P – Molting Hens Using Soy Hulls: 2. Behavioral Responses
This companion paper dealt with behavioral patterns in hens subjected to either fasting or feeding diets containing soy hulls. Aggressive pecking was not observed in the study but there was no indication of previous beak treatment. In all treatments, molted hens showed frustration in their resting, preening and non-aggressive pecking behaviors compared to controls which were not subjected to molt. These effects declined with age through 83 weeks. Neither of the papers from Brazil dealing with formulation of soy hull diets and behavior represents advances in our knowledge of molting.
Article 244P – Molt Induction Using Dietary Myceliated Grain
Myceliated grain is available as a byproduct of corn fermentation. Molt diets were prepared using the ingredient and were compared with non-fed and full-fed hens. Alternative molting diets evaluated included 90% alfalfa meal plus 10% myceliated meal. Hens which were either starved or fed 100% myceliated meal ceased production by the fifth day of evaluation. Body weight loss was significantly higher in the fasted hens (57%) compared to 8% with full fed hens with values ranging from 35% to 44% for the various diets containing myceliated meal. Myceliated meal, available as a commercial product, AF-90 was the subject of a presentation made at the Southern Poultry Science Society Meeting in January 2009. At this time it was not considered to be an acceptable ingredient to be used in molting diets based on cost relative to inert ingredients such as soy and oat hulls.
Article 84 – Evaluation of Limit Feeding Varying Levels of DDGS in Non Feed Withdrawal Molt Program for Laying Hens
Dr. Ken Koelkebeck of the University of Illinois is considered the lead researcher in the field of alternatives to initiating molt by fasting. Various combinations of wheat middlings, corn, soybean hulls and DDGS were contrasted over eight treatments extending for 28 days. Body weight loss ranged from 7% in the corn/DDGS and DDGS treatments to 25% (corn/soy hulls) with other combinations intermediate between the extremes. No consistent differences were observed among treatments throughout the post- molt period with respect to egg weight or egg production. This trial demonstrated that DDGS fed at a level of 14 lb/100 hens a day for 16 days followed by 12 lb/100 hens a day for 12 days during the molt period did not completely eliminate egg production but post molt performance was not different to feeding combinations of corn and soybean hulls. Additional studies on DDGS in molt diets are proceeding.
