Taurus Populations Research Articles

Estimating the rate of quasi-extinction of the Australian grey nurse shark ( Carcharias taurus) population using deterministic age- and stage-classified models

Grey nurse sharks off the east coast of Australia are listed nationally as “critically endangered” under Schedule 1 of the Environmental Protection and Biodiversity Conservation Act (1999) and may number no more than 300 in New South Wales and southern Queensland waters. They are an inshore, coastal dwelling species and were severely depleted by spearfishing in the 1960s. The population has continued to decline despite protection since 1984. Their life history (long-lived to 25+ years), late maturation (6–8 years), low fecundity (maximum 2 live young biennially), specific habitat requirements, limited inshore distribution, and small population size render them particularly vulnerable to extinction. We estimated the time to quasi-extinction (years elapsed for the population to consist of ⩽50 females) for the grey nurse shark population off the east coast of Australia based on current estimates of abundance and known anthropogenic rates of mortality. Estimated minimum population size was 300 as of 2002, and minimum anthropogenic mortality assessed from recovered carcasses was 12/year of which 75% were females. We modelled time to quasi-extinction using deterministic age- and stage-classified models for worst-, likely and best-case scenarios. Population size was estimated at 300 (worst), 1000 (likely) and 3000 (best). Anthropogenic mortality was added to the model assuming either all carcasses are being recovered (best), or conservatively, that only 50% are reported (realistic). Depending on model structure, if all carcasses are being reported, quasi-extinction times for worst-, likely and best-case scenarios range from 13 to 16 years, 84–98 years and 289–324 years, respectively. If under-reporting is occurring, time to quasi-extinction ranges from 6 to 8 years, 45–53 years and 173–200 years, respectively. In all scenarios modelled the grey nurse shark population will decline if no further steps are taken to remove anthropogenic sources of mortality. Because estimates of quasi-extinction rate depend on initial population size, and sensitivity analysis revealed that population rate of change was most sensitive to changes in the survival probability of the smallest length classes, obtaining precise estimates of abundance and annual survival of young females is critical.

Genetic polymorphism of milk proteins in African Bos taurus and Bos indicus populations. Characterization of variants αs1-Cn H and κ-Cn J

The polymorphism of caseins, a-lactalbumin and β-lactoglobulin was investigated in African Bos taurus (N'Dama, Baoule, Kuri) and Bos indicus (Shuwa Arab, Sudanese Flzlani) populations. The respective frequencies of alleles a and a in the N'Dama (0.89 and 0.11) and Baoule (0.92 and 0.08) breeds were almost opposite to those found in the Shuwa Arab zebu (0.22 and 0.78), a true zebu, which confirms a phenomenon already documented in the literature. Because the a/<t-Cn haplotype was strongly predominant in N'Dama and Baoul( and 0as compared to the asl/K-Cn! haplotype in the Shuwa Arab zebu (0.63), an opposite trend in frequencies was also observed between taurines and zebus at the β-Cn and rc-Cn loci. These results confirm that the polymorphism of caseins provides an efficient marker system to discriminate Bos taurus from Bos indicus origins. The Kuri was at an intermediate position, since, in this population, the a allele predominated as in taurines, while the * Correspondence and reprints

Genetic polymorphism of milk proteins in African Bos taurus and Bos indicus populations. Characterization of variants αs1-Cn H and κ-Cn J

Genetic polymorphism of milk proteins in African Bos taurus and Bos indicus populations. Characterization of variants α_s1-Cn H and κ-Cn J

Estimation of carcass and empty body composition of zebu bulls using the composition of rib cuts

Determination of body composition is very important in nutritional and growth regulation studies. However, determination of body composition by grinding and analyzing all tissues is unfeasible as an experimental routine. The objective of this study was to test methodologies for body composition estimation. Linear measurements and chemical composition of the 9-10-11th and 10th rib sections were used to estimate chemical composition of 31 Nellore (Zebu) intact males with an average 333.5 kg body weight (range of 180.5 to 496.0) and 16.1% empty body lipid (range of 10.6 to 22.1). Composition of ribs, carcass and empty body were obtained by quantitatively grinding, homogenizing and sampling all body tissues. The 9-10-11th composition was a good estimator of body composition with r² of 0.99; 0.98; 0.98 and 0.91 for estimates of kg water, lipid, protein, and ash; with low standard errors of the estimate. Results with the 10th rib cut were similar (r² of 0.98, 0.98, 0.97 and 0.88 for the same regressions). Data are in the range of published results, however coefficients of regression were statistically different from those published for Bos taurus populations. Rib cut composition is a good parameter for the estimation of chemical body composition, but specific equations must be used for Zebu animals.

RESSOURCES GENETIQUES ANIMALES DU CAMEROUN

SUMMARYThe authors presented in this article a well documented review of the local cattle, sheep and goat populations in relation to the possibility of conservation planning. While the zebu and zebulike cattle populations are in the majority, it is possibly the Bos taurus populations that are of particular interest as they represent only about 1 % of the cattle population but are reputed to be trypanotolerant. Sheep and goats are kept in small family units (approximately 5 animals) mainly for slaughter purposes on special occasions (national and religious feasts) and for cash flow purposes. A short presentation of the prevailing local breed selection schemes and the introduction of non-indigenous genetic material, mainly for cross breeding purposes are also given.

A study of the Taurus dark cloud complex

A near-infrared survey has been conducted of nearly 20 square degrees of the Taurus dark cloud complex. Additional observations have been made of selected objects detected in this survey. These observations show that recently formed stars are spread throughout the cloud and that these stars are primarily T Tauri stars or T Tauri-like stars. Two luminous objects are identified embedded in the reflection nebulae IC 359 and IC 2087. A new Herbig-Haro object is also described. The reddening law of the dark cloud material is discussed; it does not appear to be unusual in the infrared. Comparison of the young stellar population in Taurus with that in Ophiuchus suggests that the star formation mechanisms in the two regions are qualitatively different