Modelling the accumulation and transport of floating marine micro-plastics around South Africa.

Plastic pollution of South Africa's marine environment is widespread, yet limited research exists on the distribution, accumulation and transport of plastic debris around South Africa. In this paper, numerical modelling is used to provide a first approximation of the pathways and accumulation of marine micro-plastics around South Africa. To account for a range of plastic classes, particles with two different densities are considered. Low-density (LD) particles represent low- and high-density polyethylene while high-density (HD) particles are representative of Polyethylene terephthalate and Polyvinyl chloride. While the majority of micro-plastic particles that enter the ocean from the five major coastal urban-industrialised centers beach along the coastline of South Africa, a third is exported to the open ocean. LD and HD particles are primarily exported to the South Atlantic and South Indian Ocean, respectively. Particles that beach along South Africa's coastline tend to accumulate in close proximity to the coastal urban-industrialised centers.

A new chondrodystrophy mutation in Japanese quail (Coturnix japonica).

A second form of hereditary chondrodystrophy (ch-2) has been discovered in a selected line of Japanese quail, Coturnix japonica. This form of chondrodystrophy is autosomal and recessive, characterized by an overall shortening and bending of the long bones of the wings and legs, slight dwarfing of the trunk, bulging of the eyes, flattening of the head, and a parrot beak. The shortened long bones vary in regard to the amount of bending from nearly straight to bends of up to 90 degrees in the midshaft region. In severe cases, the bend is evident as a protuberance of the skin. Affected embryos usually survive the 18-day incubation period. Several have hatched, but most survived no longer than 4 days after hatching. Only one female has survived long enough to lay eggs. Testcrosses indicated that this mutation is not allelic to micromelia.

Effects of light conditioning on reproduction in partridge.

Reproductive response was measured in two lines of chukar partridge given conditioning light treatments of either 8 hr light:16 hr dark (8L:16D) at 50 lx or 16L:8D at .1 lx for 4, 6, or 8 weeks, respectively. Birds were recycled to lay using the same conditioning light treatments. During both lay cycles, all birds received 16L:8D at 100 lx. The results indicate that both conditioning light regimens were effective in terminating postjuvenile and postlay refractoriness. Hens given a conditioning light treatment of 8L:16D at 50 lx reached sexual maturity earlier, and produced more eggs and more viable chicks, and males maintained fertility longer, compared to birds conditioned under 16L:8D at .1 lx. Light conditioning periods of 6 and 8 weeks were superior to those of 4 weeks. For maximum reproductive performance in partridges, a short day photoperiod of 8L:16D at 50 lx is recommended for successful interruption of either postjuvenile or postlay refractoriness.

Shank length for determining sex in chukars.

Shank length measurement of greater than or equal to 60 mm for males and less than 60 mm for females was used to predict sexes in male and female chukar partridges (Alectoris chukar) at 8, 10, 12, 20, 32, and 64 weeks of age. Growth of the shank is nearly complete at 10 weeks of age, whereas growth of body tissue continues to about 20 weeks of age. The best prediction of sexes was made at 10 weeks of age with an accuracy of about 95%. At 10 weeks of age, the accuracy for predicting males was higher than for females (98.5% vs 93%). At 64 weeks of age, best accuracy of sexes was made using a shank measurement of greater than or equal 61 mm for males and less than 61 mm for females. This technique to differentiate between sexes requires only a single shank measurement taken at 10 weeks of age and provides the grower and avian biologist with a reliable way of separating sexes for purposes of marketing, restoration, or selection of breeders at early ages.

The effect of light intensity, temperature, and diet on growth in red-legged partridge.

Three hundred Red-legged partridge chicks ( Alectoris graeca) were divided into two groups and fed starter diets calculated to contain 24.5 and 24.9% crude protein and 2646 and 2662 kcal/kg metabolizable energy, respectively. One diet consisted of 5% fish meal while the other contained all vegetable protein. One-half of the birds on each diet were grown under fluorescent light intensity of 300 lx; the remainder received 5 lx. The results indicated that neither the source of protein nor intensity of light had an effect on the rate of growth to 8 weeks of age. At 8 weeks of age, the birds were randomly divided among three climatic chambers and kept under a constant temperature of either 18.3, 23.9, or 29.5 C. At 12 weeks of age, one-half of the birds in each chamber were fed a 20% turkey grower diet; the remainder received equal parts by weight of the turkey grower diet and whole milo . Individual body weights and feed consumption were measured biweekly. Best growth was obtained in birds kept at 29.5 C and fed equal parts of turkey grower and milo from 12 to 30 weeks of age.

The effect of ambient temperature and energy level on reproduction in Red-Legged partridges.

The effects of temperature and dietary energy on various reproductive parameters were studied in Red-Legged partridges (Alectoris graeca) reared in three environmental chambers at either 18.3, 23.9, or 29.5 C. These birds were then cycled through two consecutive production periods. In Period 1, at 38 weeks of age, the birds in each chamber, 118 pair total, were divided into four subgroups and fed a diet containing either 2600, 2800, 3000, or 3200 kcal/kg of metabolizable energy. The energy to protein ratio was held constant at 186. In Period 2, at 63 weeks of age, chambers with the lowest and highest temperatures were changed from 18.3 to 15.6 C and 29.5 to 32.2 C, respectively. Only the lowest and highest energy diets were used. In both periods, the birds kept at higher temperatures and fed the high energy diets consumed significantly less feed (P less than .05) than the other comparable groups. Hatchability was significantly higher (P less than .05) in groups fed the 3000 and 3200 kcal/kg diets as compared to the 2600 kcal/kg diet group. In Period 2, egg production increased in all groups, but birds kept at 32.2 C laid significantly fewer (P less than .05) eggs per bird than those kept at 15.6 and 23.9 C, respectively. The best performance, as measured by salable chicks produced per hen, was obtained in the group kept under a constant temperature of 23.9 C and fed the high energy diet (3200 kcal/kg).