Selection for food conversion in broilers: Direct and correlated responses to selection for body‐weight gain,food consumption and food conversion ratio

1. Direct and correlated responses were determined after five generations in four lines of chickens selected either for increased body‐weight gain (line W), for increased food consumption (line F), for decreased food conversion ratio (line E), or at random (line C).

2. Realised heritability estimates calculated after five generations of selection were : 0–37 + 0.04 for weight gain (WG); 0.44 + 0.05 for food consumption (FC); 0.21 + 0.04 for food conversion ratio (FCR).

3. Realised genetic correlation estimates were: WG and FC, +0.71 ±006; WG and FCR, ‐0.40±0.09; FC and FCR, +0.27 + 0.09.

4. Zero‐generation heritability and genetic correlation estimates were greater than the realised estimates, and sex linkage appeared to be important in the expression of all three traits.

5. The genetic correlation between FC and FCR was asymmetrical with considerable positive response in FCR in line F (r_g = +0.79) but negligible response in FC in line E (r_g = —0.01).

6. There was an apparent plateau in response in FCR in line E from the third to the fifth selected generations.     

The hen's egg: Evidence on the mechanism relating shell strength to loading rate

1. The decrease in strength of an egg shell which is known to accompany an increase in the period of time over which a load is applied might come about by either of two mechanisms: a decrease in the strength of the material constituting the strong, outer layer of the mineral shell, or a decrease in the thickness of this layer brought about by deepening of the crevices that are normally present between adjacent crystal columns in the weak, inner layer of the shell.

2. Experiments designed to discriminate between these mechanisms are described: the results indicate the second mechanism.

3. This mechanism offers explanations for various other shell phenomena, including delayed fracture under a static, cyclical or recurrent load.

4. The main implication for the poultry industry is that any external insult to a shell is likely to weaken it by doing damage that is local, internal, irreparable and cumulative, even though it may be invisible from the outside.     

Production of primary cell cultures on a semi-industrial scale. 1. Modification of the trypsinization procedure--possible means to improve cell yield

To produce large quantities of primary cell suspensions on efficient technique is described which is named "Biomix-Method". By this technique first tissue mince is performed automatically using tissue amounts between 300 g and 500 g. Trypsinization takes place in a three-litre trypsinization vessel using a stirring mechanism according to a defined trypsinization mode. In regard to optimal cell seeding concentration and a justifiable productivity one kidney of newborn or suckling calf yields 6--9 1 cell suspension and that of piglet 1,8-2,3 1, respectively. Proliferation behaviour and effectivity of primary cells are discussed and compared with other cell systems.     

Mucopolysaccharidosis in a domestic short-haired cat--a disease distinct from that seen in the Siamese cat.

A 10-month-old male domestic short-haired cat was examined because of progressive lameness, a broad face with depressed nasal bridge, small ears, corneal clouding, and multiple bone dysplasia. The cat excreted excessive amounts of glycosaminoglycan (a component of connective tissue) in its urine and had evidence of lysosomal storage of glycosaminoglycans in fibroblasts and neurons. Activity of alpha-L-iduronidase, a lysosomal enzyme involved in glycosaminoglycan degradation, was deficient in cultured fibroblasts and leukocytes. The mucopolysaccharidosis was distinct from that seen in Siamese cats in terms of the pathologic changes and the specific enzyme deficiency.     

AN OESOPHAGEAL DIVERTICULUM IN A DOG

An 11-month-old male Miniature Poodle was found to regurgitate small volumes of fluid and food particles due to a diverticulum in the thoracic oesophagus. The diverticulum was removed surgically. Histologically the wall contained extensive scar tissue. Longterm recovery was uneventful and 5 months after surgery the dog is in good health     

Bovine abortion associated with mixed Movar 33/63 type herpesvirus and bovine viral diarrhea virus infection.

A herpesvirus and cytopathogenic bovine viral diarrhea virus were isolated from a bovine fetus aborted in the 6th month of gestation. The herpesvirus was serologically indistinguishable from bovine herpesviruses DN-599 and Movar 33/63.