Mechanistic studies on carboxypeptidase a from goat pancreas — part II: Evidence for carboxyl group

Studies with substrate analogues and the pH optimum indicated the involvement of carboxyl group in the active site of goat carboxypeptidase A. Chemical modification of the enzyme with 1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide methoI -p-toluene sulphonate, a carboxyl specific reagent, led to loss of both esterase and peptidase activities. Protection studies showed that this carboxyl group was in the active site and was protected by Βp-phenylpropionic acid and glycyl-L-tyrosine. Kinetic studies also confirmed the involvement of carboxylic group because the enzyme modification with water soluble carbodiimide was a two step reaction which excluded the possibility of tyrosine or lysine which are known to give a one step reaction with this reagent     

The effects of different PMSG doses on estrus behavior and pregnancy rate in Angora goats

Artificial insemination protocols depend on efficient behavioral estrus detection and insemination time in Angora goat. Therefore, we aim to determine the accuracy of an estrus scoring system in Angora goats with different PMSG doses during the breeding season. Does (n: 260) were randomly divided into three groups: group-1 (n: 93), group-2 (n: 85) and group-3 (n: 82). All animals received an intravaginal sponge on day 0 for 11 days, and on the day of sponge insertion 150 μg prostaglandin F2Α was administered. Pregnant mare’s serum gonadotropin was injected 300, 400 and 500 IU intramuscularly 24 h before sponge removal to groups 1, 2 and 3, respectively. Estrus signs were detected with a teaser buck, 24 h after sponge removal according to a visual scoring system. Artificial insemination was performed with 0.25 ml fresh diluted semen at 43 to 45 h after sponge removal. Differences were observed within PMSG groups in terms of standing, tail wagging, courtship behavior, vaginal discharge and vaginal hyperemia (P<0.001). Nevertheless, the most accurate indicators of estrus that result in pregnancy were tail wagging and courtship behavior followed by standing estrus (P<0.05). According to the results obtained, 300 IU PMSG dose is sufficient, both to inseminate at a fixed time (43 to 45 h after sponge removal) and to record the estrus behavior by teaser male 24 h after sponge removal. Higher PMSG doses (400 to 500 IU) altered the timing of ovulation; specifically, 500 IU dose shortened the duration of estrus behaviors. In conclusion, even though the different doses of PMSG displayed similar effects on estrus synchronization and pregnancy rates, we concluded that tail wagging, courtship behavior and standing heat are the most reliable estrus signs for artificial insemination in Angora goat.     

Smallholder experiences with dairy cattle crossbreeding in the tropics: from introduction to impact

Crossbreeding of indigenous tropical and improved western dairy cattle breeds as tool to improve dairy cattle performance on smallholder farms has been widely advocated, criticised and yet applied. The government of Ethiopia supported this technology for decades but adoption rate is low. Constraints are documented but there is little information about farm level introduction and development of crossbreeding. A total 122 smallholders with mixed crop livestock farms and at least 8 years of successful crossbreeding were interviewed using a pre-tested questionnaire in two contexts in Amhara Regional state in north-western Ethiopia. Crossbreeding initiator was either uncoordinated government extension or a coordinated development project, also implemented with governmental support. Qualitative and quantitative data on farmers’ motivations, crossbreeding introduction, initiator support, breeding adaptation and impacts at farm level were analysed. Results show that even though motives vary between contexts the underlying reason to introduce crossbreeding was economic profit. To be able to introduce crossbreeding support of initiators (e.g. extension) and other farmers was essential. The crossbreeding introduction context had some influence. Governmental actors were the main source of support and supplier of exotic genetics but the farmer network acted as safety net filling gaps of government support. Breeding strategies focused on performance increase. A lack of basic understanding of crossbreeding has been identified. A surprising, probably biased, result was general satisfaction with initiator support and with breeding services. It was challenged by the high proportion of farmers unable to follow a breeding strategy due to insufficient bull and/or semen supply. Crossbreeding changed the smallholder production system to a high input – high output system. Except for crossbred adaptation problems, challenges were ranked context specific and influenced by the initiator. Farmers perceived crossbreeding as success and recommended it. We conclude that farmers can realize income increase with crossbreeding. The complexity of this technology, high initial investment and the need for support services and external production inputs are probable reasons why crossbreeding uptake is low. Improving the availability of semen and/or bulls must be the top priority for breeding service providers to enable farmers to follow a breeding strategy and reach a suitable and sustainable herd performance. Access to investment capital, input supply, strong technical support and market linkages are crucial for successful crossbreeding.     

Restriction fragment length polymorphisms in dairy and beef cattle at the growth hormone and prolactin loci

Two bovine populations, a Holstein-Friesian dairy stock and a synthetic (Baladi X Hereford X Simmental X Charolais) beef stock, were screened for restriction fragment length polymorphisms (RFLPs) at the growth hormone and prolactin genes. Most RFLPs at the growth hormone gene are apparently the consequence of an insertion/deletion event which was localized to a region downstream of the structural gene. The restriction map for the genomic region including the growth hormone gene was extended. Two HindIII RFLPs at the growth hormone locus, as well as several RFLPs at the prolactin gene, seemed to be the consequence of a series of point mutations. The results are discussed in terms of the possibility that minor genomic variability underlies quantitative genetic variation.     

Real-time ultrasonic fetal head measurement and gestational age in dairy goats

Dairy breed goat fetuses (n = 219) of known gestational age (Day 39 to Day 100) were examined transabdominally using a real-time ultrasound scanner with a 5 MHz linear-array transducer. Maximum head width was measured in symmetrical images using electronic linear distance calipers. This biparietal diameter (BPD) can be accurately measured as early as Day 40, but measurement becomes difficult after Day 105 of gestation due to the variability of fetal location and posture. The uniform, linear increase in BPD in the second trimester should allow for the accurate assignment of gestational age for doe confinement or induction of kidding.     

Immunohistochemical localization of keratin in bull,goat, and sheep anterior pituitary glands

Summary Immunohistochemical localization of keratin, an intermediate filament protein, was studied in bull, goat, and sheep anterior pituitary glands, i.e., in animals of the order Artiodactyla. Strong immunoreactivity was detected in the cells of the marginal layer of bull and goat, as well as in cysts or large follicles in the anterior lobe of all 3 species. In addition, a number of stellateshape cells were immunoreactive for keratin and were distributed throughout the anterior lobe. The localization of keratin-positive cells in light-microscopic preparations correlated precisely with the localization of folliculo-stellate cells in adjacent ultrathin sections. In ultrastructural studies, many slender and elliptical membranous components which were different from smooth endoplasmic reticulum were observed in the cytoplasm of the some keratin-positive cells. Some of the folliculostellate cells in the 3 species were also immunoreactive for the subunit of S-100 protein, which exists in some epithelial cells. On the other hand, immunolocalization of glial fibrillary acidic protein, a glial cell marker, could not be demonstrated in the anterior pituitary glands of the 3 species studied. These results suggest that keratin-positive folliculo-stellate cells express epithelial-like characteristics.     

Pastoral dairy marketing and household wealth interactions and their implications for calves and humans in Ethiopia

Surveys of pastoral households in a semi-nomadic Borana community during 1987–1988 were used to test the hypothesis that poorer families living closest to a market town would be most affected by the enhanced opportunity to sell dairy products, which would intensify competition between people and calves for milk and have negative implications for calf management. These poorer families indeed reported the highest rates of milk offtake per cow, and the milk increment was probably sold to purchase more grain for human consumption at the expense of milk intake for the calf. Consequently, this strategy may increase the susceptibility of malnourished calves to disease, especially those from lower-producing dams. Benefits of improved human energy intake from grain and retention of livestock capital must be weighed against risks of calf death and possible malnutrition of people from milk restriction when assessing dairy marketing trade-offs that are most acute for the poor. Opportunity to sell dairy products at favorable terms of trade helps the poorest people survive, and their risks could be mitigated by policies that facilitate grain marketing in the rangelands and interventions that improve calf feeding management, diversify human diets, and create alternative opportunities for women to generate income. The households postulated to be most at risk were identified from a complex, but logical, interaction among factors of distance to market, household wealth, and the quality of milking cows held. This indicates that targeting such needy groups for development assistance may require a more detailed and interdisciplinary analysis of production systems than is commonly practiced.     

Isolation and partial sequence of goat spleen prothymosin α

Goat prothymosin , a highly acidic polypeptide of pl 3.5, 109 amino acid residues, has been isolated from lymphoid and non-lymphoid tissues of young female goats. Unlike rat, murine and porcine prothymosins , goat prothymosin appears at a higher concentration in the spleen compared with the thymus. The sequence of segments of the polypeptide involving known mutations has been determined, by automatic sequencing of its tryptic peptide fragments. The acidic amino acid-rich segment in the middle of the molecule, including residues 49–83, has not been sequenced. Goat prothymosin closely resembles bovine prothymosin , with only one substitution, proline for alanine at position 85. It also resembles human prothymosin , with only three substitutions. It differs more significantly from rat and murine prothymosins , by two deletions and three substitutions. The results show the highly conserved nature of the molecule, with substitutions at given positions only.Abbreviations ProT Prothymosin - T₁ Thymosin ₁ - MLR Mixed Lymphocyte Response - HPLC High Performance Liquid Chromatography - RIA Radioimmunoassay - B Aspartic acid or Asparagine - Z Glutamic acid or Glutamine     

In vitro culture of the strobilar stage of Echinococcus granulosus from protoscoleces of human, camel, cattle, sheep and goat origin from Kenya and buffalo origin from India

Protoscoleces from human, camel, cattle, sheep, goat (all from Kenya) and buffalo (from India) hydatid cysts were cultured under identical conditions in vitro using the diphasic culture system of Smyth (1979b). Organisms from all sources grew and segmented in culture. Genital anlagen developed in all cultured worms but further genital differentiation occurred only in cultures of cattle (testes) and camel (testes and genital pore) material. The possible significance of these results is discussed in relation to the general epidemiology of hydatid disease and the potential infectivity of the different strains to man.     

Variation in the oxytocin content of caprine corpora lutea across the breeding season

Ovarian tissues were obtained from cyclic goats during the early, mid and late breeding season. Immunoreactive oxytocin was measured by RIA in tissue extracts after chromatography on octadecylsilica cartridges. Luteal oxytocin concentrations were significantly greater during the early breeding season than during the mid or late breeding season. Oxytocin is luteolytic in goats. High concentrations of luteal oxytocin may be related to the high incidence of short estrus at the onset of the breeding season.