Spent Hen Research Articles

Frequency of Salmonella enteritidis and Other Salmonellae in the Ceca of Spent Hens at Time of Slaughter

A study was conducted to determine the frequency of Salmonella enteritidis (SE) and other Salmonella serovars in the cecal contents of spent laying hens at a hen-processing plant in the southeastern United States over a 4 1/2-month period, from October 1990 through February 1991. A total of 1920 pooled cecal samples (three ceca per sample) from 38 flocks representing 23 producers were obtained and tested for the presence of SE and other Salmonella serovars. A total of 359 samples (18.7%) from 37 of the 38 flocks (97.4%) showed characteristic reactions for salmonellae on triple sugar iron agar (TSIA) slants. Twenty-nine of the 359 Salmonella-positive samples (8.1%) were Group D-positive, all of which were found to be SE on further serotyping. The SE-positive samples were from seven of the 38 flocks (18.4%); four flocks originated from the USDA/APHIS-designated Northern Region of the United States, and three were from the Southeastern Region. Serotyping of the 330 TSIA-positive Group-D negative Salmonella revealed 37 different serovars. S. heidelberg, the predominant serovar, was identified in 49.1% of these isolates.

Effects of induced moulting on immune responses of hens.

1. The potential for induced moult to be a stressor and therefore alter the immune response in hens was examined. Spent hens from White Leghorn and White Rock layer flocks were induced into a moult by withdrawal of food and the effects on the humoral and cellular immune responses of these birds were examined. 2. Lymphocyte numbers were lower in moulted birds compared with nonmoulted controls. 3. Antibody responses to sheep red blood cells or Brucella abortus antigen were largely unaffected. 4. The delayed type hypersensitivity response to the skin sensitiser dinitrofluorobenzene (DNFB) was depressed during the period of food withdrawal but recovered when feeding resumed. 5. Induced moulting probably has a negative effect on the cellular component of the immune system of the moulted birds.

Ascorbic Acid as Related to Tibia Strength in Spent Hens

Three studies involving 450 spent S.C.W.L. individually caged hens were conducted during the winter months. It was found that feeding six different levels of ascorbic acid at different time intervals from three days to four weeks had no significant effect on tibia breaking strength, serum calcium, egg production or percent tibia ash. There was a trend for a numerical decrease in tibia breaking strength when hens fed ascorbic acid were compared to controls. A statistical difference was noted between strains when tibia strengths were compared.

A Procedure Study of Bone Breakage in Spent Hens

PROCESSING of Leghorn type laying hens frequently results in the shattering of keel bones, rib cages and clavicles. Birds reared in cages present more of a problem than those reared on the floor. Bone breakage is greater with caged birds arriving at the processing plants and the bone breakage is further compounded by the de-feathering equipment. In extreme cases as many as 85 to 95 percent of the carcasses are not acceptable for deboning and further processing (Kralis, 1968).It has been shown that the laying hen will deplete its skeletal muscle of calcium when the calcium level of the diet is low (Common, 1938; Taylor and Moore, 1954). The percent of bone ash drops when pullets are fed a diet low in calcium (Taylor and Moore, 1954). Both bone ash and breaking strength appear to be related to bone strength (Rowland et al., 1967a, 1968a). Increasing the calcium level…