Dissection of ancestral genetic contributions to Creole goat populations.

Goats have played a key role as source of nourishment for humans in their expansion all over the world in long land and sea trips. This has guaranteed a place for this species in the important and rapid episode of livestock expansion triggered by Columbus' arrival in the Americas in the late 1400s. The aims of this study are to provide a comprehensive perspective on genetic diversity in American goat populations and to assess their origins and evolutionary trajectories. This was achieved by combining data from autosomal neutral genetic markers obtained in more than two thousand samples that encompass a wide range of Iberian, African and Creole goat breeds. In general, even though Creole populations differ clearly from each other, they lack a strong geographical pattern of differentiation, such that populations of different admixed ancestry share relatively close locations throughout the large geographical range included in this study. Important Iberian signatures were detected in most Creole populations studied, and many of them, particularly the Cuban Creole, also revealed an important contribution of African breeds. On the other hand, the Brazilian breeds showed a particular genetic structure and were clearly separated from the other Creole populations, with some influence from Cape Verde goats. These results provide a comprehensive characterisation of the present structure of goat genetic diversity, and a dissection of the Iberian and African influences that gave origin to different Creole caprine breeds, disentangling an important part of their evolutionary history. Creole breeds constitute an important reservoir of genetic diversity that justifies the development of appropriate management systems aimed at improving performance without loss of genomic diversity.

Genetic diversity and patterns of population structure in Creole goats from the Americas.

Biodiversity studies are more efficient when large numbers of breeds belonging to several countries are involved, as they allow for an in-depth analysis of the within- and between-breed components of genetic diversity. A set of 21 microsatellites was used to investigate the genetic composition of 24 Creole goat breeds (910 animals) from 10 countries to estimate levels of genetic variability, infer population structure and understand genetic relationships among populations across the American continent. Three commercial transboundary breeds were included in the analyses to investigate admixture with Creole goats. Overall, the genetic diversity of Creole populations (mean number of alleles = 5.82 ± 1.14, observed heterozygosity = 0.585 ± 0.074) was moderate and slightly lower than what was detected in other studies with breeds from other regions. The Bayesian clustering analysis without prior information on source populations identified 22 breed clusters. Three groups comprised more than one population, namely from Brazil (Azul and Graúna; Moxotó and Repartida) and Argentina (Long and shorthair Chilluda, Pampeana Colorada and Angora-type goat). Substructure was found in Criolla Paraguaya. When prior information on sample origin was considered, 92% of the individuals were assigned to the source population (threshold q ≥ 0.700). Creole breeds are well-differentiated entities (mean coefficient of genetic differentiation = 0.111 ± 0.048, with the exception of isolated island populations). Dilution from admixture with commercial transboundary breeds appears to be negligible. Significant levels of inbreeding were detected (inbreeding coefficient > 0 in most Creole goat populations, P < 0.05). Our results provide a broad perspective on the extant genetic diversity of Creole goats, however further studies are needed to understand whether the observed geographical patterns of population structure may reflect the mode of goat colonization in the Americas.

Effect of infectious status and parity on somatic cell count and California mastitis test in pampinta dairy ewes.

The relationship between somatic cell counts (SCC) and California mastitis test (CMT) results according to the infectious status of mammary halves and parity of Pampinta dairy ewes was evaluated. Tests were associated to bacteriological analysis and classified into three groups: uninfected (negative culture), infected by minor pathogens and infected by major pathogens. Coagulase-negative Staphylococcus (32.4%), Micrococcus spp. (32.4%), Corynebacterium spp. (5.4%), and Bacillus spp. (1.4%) were the minor pathogens isolated, while Staphylococcus aureus (27%) and Escherichia coli (1.4%) were the major pathogens isolated. A good correlation was found between the CMT and SCC, which included inflammatory and epithelial cells (r = 0.64; P < 0.0001). SCC averages for the CMT scores shown in parentheses were 223 576 (0); 245,248 (1); 397,778 (2); 1,159,109 (3) and 2,460,833 (4) cells/ml. The correlation between SCC and the infectious status of udder halves was 0.58 (P < 0.0001). The relationship between SCC and CMT profiles and infectious status studied by a discriminant analysis showed, with an accuracy of 65%, three infectious status groups. SCC arithmetic means were 244,470 cells/ml for negative culture, 1,044,100 cells/ml for minor pathogens and 2,045,652 cells/ ml for major pathogens. With the exception of 1-year-old ewes, no significant differences were observed in SCC as affected by age or parity.

Fluoride-induced early teeth wearing in Argentinian cattle.

The relationship between observed early teeth wearing in cattle and the existence of large areas where excess fluoride in underground water prevails in Argentina, but has never been studied. Average values of bone fluoride exceeding 5000 ppm and well water containing up to 10.5 ppm of this element were found in a farm (ETWF) where early teeth wearing is observed, while in a control farm (NETWF), those values were 1480 ppm and 3.0 ppm respectively. Urine samples from animals from the ETWF contained almost 4 times more fluoride than those from the latter. Forage in both farms contained about the same levels of fluoride (15 to 25 ppm). None of the farms was exposed to industrial, volcanic, or geothermal activity. Lactating and adult animals were transferred from one farm to the other. After 30 months, adult animals from the NETWF showed no damage in teeth, while adults from the ETWF continued a rapid teeth wearing. Young animals from the NETWF developed severely damaged permanent teeth, while young animals from the ETWF developed normal teeth. We concluded that the problem exists in the ETWF and being a standard farm, the condition could be extrapolated to other areas.

Spiculopteragia spiculoptera, S. asymmetrica and Ostertagia leptospicularis from Cervus elaphus in La Pampa, Argentina.

The nematode species Spiculopteragia spiculoptera, Spiculopteragia asymmetrica and Ostertagia leptospicularis were recovered from the abomasum of wild red deer, Cervus elaphus, in the forest area of the semi-arid Pampeana Region of La Pampa (Argentina) for the first time. Oesophagostomum venulosum and Dictyocaulus spp. were also found.

Effects of an integrated control programme with ivermectin on growth, carcase composition and nematode infection of beef cattle in Argentina's western pampas.

The effect of previous pasture management and ivermectin treatment on gastrointestinal parasitism, weight gain and carcase composition of steers was studied in the semiarid Pampeana region of Argentina from April 1986 to April 1987. Three groups, each of 15 weaned calves, were grazed on separate lucerne pastures. Group 1 control calves, which grazed paddocks previously grazed by nematode-infected weaners and yearlings with a high nematode egg output, were only medicated when heavy parasitism was recorded. Group 2 calves, which grazed paddocks previously infected by steers at least two and a half years old with low nematode egg output, were treated strategically with ivermectin. Group 3 calves, which grazed on 'clean' paddocks, were treated monthly with ivermectin. Group 1 calves showed heavy parasitism and parasitological parameters were higher than in groups 2 and 3. The liveweight gain responses of groups 2 and 3 were significantly greater than those of group 1 (P less than 0.001) during autumn, winter and early spring. At the end of the study when cattle reached market condition, the liveweight gains of groups 2 and 3 were 74.1 and 81.9 kg, respectively, greater than group 1. Carcase analyses showed significantly greater weight and killing-out percentages in groups 2 and 3 than in group 1. Reduced total bone, muscle and fat weights were observed in group 1.

Epidemiology, effects and control of nematode infections on Zebu crossbred, Hereford and Hereford X Brahman calves of Argentina's western pampas.

Gastrointestinal parasitism of Zebu crossbred (Z), Hereford (H), and Hereford X Brahman (HB) weaned steer calves was observed from March 1985 to May 1986. Three groups of 60 calves were randomised and in each group the three breeds were equally present. Calves in GI were untreated, in GII were treated strategically and in GIII treated monthly with anthelmintic. The effects of anthelmintic treatments on the growth of cattle were assessed by comparing mean live-weight gain (MLG) responses of treated and untreated calves grazing the same permanent pasture. Worm recovery and egg counts increased from autumn to winter. After abundant July rainfalls, herbage infective larvae (L3) and worm burdens (mainly Ostertagia) reached the highest levels and Z calves presented symptoms of clinical parasitism. After high availability of L3 in spring, L3 and egg counts decreased to the end of the study. From the end of winter until summer a high percent of inhibited Ostertagia EL4 was seen. Blood samples showed reduced serum copper lower levels for GI. MLG responses of Z treated calves were significantly higher during the autumn-spring and summer-autumn periods. MLG responses of treated H calves were significant only during the winter-spring period. For HB calves there were no significant MLG responses during any period. The highest monthly treatment response was observed during winter and early spring. All strategic treatments gave significant MLG responses in spring and late summer. Initial effects of parasitism, from autumn until early spring had the greatest consequences in current and later productivity. For Z calves herbage L3, worm burdens, egg counts and MLG responses were higher than for H and HB calves. The Z breed were significantly heavier (+22.7%) at the end of the experiment in GIII than in GI. Similar trends were recorded, significantly, for H breed (+17.7%) and not statistically significant for HB (+12.7%). Under our temperate conditions it seems that H and HB calves showed greater capacity to resist nematode infection than Z calves.