Concepta McManus

Fatores ambientais e parâmetros genéticos para características produtivas e reprodutivas em um rebanho nelore no estado do Mato Grosso do Sul

The objective of the present work was to investigate the effects of some genetic and environmental factors on production (weaning weight WW; eighteen month weight W18) and reproduction (scrotal perimeter at 18 months SP18; calving interval CI; age at first calving AFC; True fertility TF, calving date CD) traits in a Nellore cattle herd in the Mato Grosso do Sul State, Brazil. The observations were analysed using the least squares methodology, and the statistical models included the fixed effects: year (YB) and month (MB) of calving, interaction YB*MB, sex (S) of animal (except for W18, SP18 and AFC) and calving number. Significant effects were found for all factors studied on WW, and animals born in August (179 kg) and December (156 kg) had highest and lowest WW respectively. The male calves (174 kg) were heavier at weaning than females (162 kg), a difference of 7.4% in favour of males. No tendency was observed in terms of mean values over the years for this trait. W18 was influenced only by birth year, with a mean value of 281.0 kg. Only calving number did not influence Scrotal perimeter (SP18), which had a mean value of 26.8 cm. The mean CI was 465 days, and all effects were significant, except for calf sex. TF was significantly influenced by all effects studied, and had a mean value of 144 kg. Age at first calving was high (1.279 days or 41.93 months) and influenced by month and year of calving. In terms of calving date, month and year were significant effects, as was the interaction between these effects but sex and calving number did not affect this trait. Based on estimates of heritability, permanent environment, as well as on genetic and phenotypic correlations, estimated using MTDFREML, it was concluded that these traits should respond to direct selection, except for RF and AFP. Genetic correlations between production traits were favourable, indicating the possibility of genetic progress through indirect selection.

Genetics and breeding of sheep in Brazil

Studies in genetics and breeding of sheep in Brazil have increased significantly in recent years. These involve research in characterization, breeding and crossing sheep using new technologies available incorporating both classical quantitative and molecular genetics. Improvements in statistical techniques, computational resources as well as analysis of DNA and gaps in present knowledge and opportunities for possible research are pointed out. There is a need for greater interaction between various groups working in the country as well as interactions with other disciplines such as Geographical Information Systems, Statistics, Bioinformatics, as well as biological studies such as physiology and proteomics. Genetica e melhoramento de ovinos no Brasil RESUMO - Estudos em genetica e melhoramento de ovinos no Brasil tem aumentado significativamente nos ultimos anos. Estes envolvem pesquisa em caracterizacao, criacao e cruzamento de ovinos utilizando as novas tecnologias disponiveis, incorporando tanto a genetica quantitativa classica e molecular. Sao abordadas sugestoes para melhorias nas tecnicas de estatistica, nos recursos computacionais, bem como na analise de DNA e nas lacunas no conhecimento atual e possibilidades de possiveis investigacoes. Ha uma necessidade de maior interacao entre varios grupos de trabalho no pais, bem como as interacoes com outras disciplinas, como Sistemas de Informacao Geografica, Estatistica, Bioinformatica, bem como estudos biologicos, como fisiologia e proteomica.

Genetic variability of the Brazilian hair sheep breeds

The objectives of this work were to investigate the genetic structure of the Brazilian hair sheep breeds and to determine the origin of the Santa Ines breed. Molecular similarity was determined using Randomly Amplified Polymorphic DNA - Polymerase Chain Reaction markers in 238 individuals from five naturalized sheep breeds: Santa Ines (48 animals), Rabo Largo (48), Somali (48), Morada Nova (48) and Bergamasca (46), collected in Goias, Sergipe, Bahia, and Ceara States as well as in the Federal District. Fifty-four loci were selected from 19 primers, after a pilot test using 140 primers. Qualitative analyses indicate diagnostic markers for all breeds. All breeds were significantly different from each other. Interbreed differences were explained by 14.92% of the total variation. Santa Ines clustered with Bergamasca (97% bootstrap) and with Rabo Largo, composing the third member of the group (81% bootstrap) while Morada Nova and Somali breeds clustered separately. Each breed should be considered as a separate management and conservation unit, and special care should be taken with Rabo Largo, Morada Nova and Somali breeds, represented by small herds in Brazil.

Características biométricas testiculares para avaliação de touros zebuínos da raça Nelore

ABSTRACT - The objective of this study was to analyze the testicular volume and shape in young males of Nellore Zebu breed and their importance for the evaluation and selection of sires. Four hundred and forty two males, from 12 to 18 month of age, were examined for scrotal circumference (CE), length (COMP), width (LARG) and testicular volume (VOL). The animals were divided in two groups (G1 and G2) according to their date of birth. The VOL was calculated by the formula: VOL = 2[(r2) x P x h], where r, h and P are LARG/2, length and 3.14, respectively. The mean values of CE, COMP, LARG and VOL at 12 month of age were 184.89±15.79 mm, 65.96±6.48 mm, 2.58±4.63 mm and 113.80±42.03 cm3, and at 18 months of age were 236.81±mm, 79.31±11.16 mm, 42.92±5.83 mm and 239.26±90.56 cm3, respectively. The parameters at 12 and 18 months of age were influenced by contemporary groups, being highly correlated. The testicular shape was considered as a length to width ratio, being recorded five forms: long (ratio £ .5), long moderate (.51 to .626 ratio), long/ovoid (.626 to .750 ratio), ovoid/spheroid (.751 to .875 ratio) and spheroid (> .875 ratio). 87% of the animals presented the long shape and, in 74%, the testicular shape changed with the age. All the parameters were influenced by testicular shape, and the testis grew in width. The results suggest that the selection of young bulls should consider the testicular volume besides the possible change in the testicular shape.

Skin and coat traits in sheep in Brazil and their relation with heat tolerance.

The objective of this study was to evaluate and compare physical parameters in groups of sheep with different phenotypic characteristics in the Centre-west region of Brazil. Five groups of sheep, with nine animals per group, were selected, three groups of Santa Inês animals with different coat colours (white, brown and black), one group with crossbred animals (Santa Inês × Bergamasca) and one group with animals of the Bergamasca breed. The following traits were evaluated: coat thickness, number and length of hair, pigmentation level in the coat and the skin as well as the percentage area of sweats glands in the skin tissue, carried out by histological analysis. The number of hairs and the area of sweats glands were not significantly different between the evaluated groups. The Bergamasca breed showed low pigmentation of the skin and long hairs. The levels of pigmentation of the hair and of the skin were highly correlated. Between the Santa Inês groups, the group with white hair showed the better parameters for heat adaptation, while the brown hair group showed the lower heat adaptation when compared with another hair breed groups.

Efeitos Genéticos e Fenotípicos sobre Características de Produção e Reprodução de Ovinos Deslanados no Distrito Federal

This study aims to estimate genetic and phenotypic parameters for the Morada Nova, Santa Ines e crossbred Texel x Morada Nova in Federal District of Brazil. Data were available on 2337 lambings over a period of 14 years (1986 to 1999) from a commercial holding for meat production. The herd had no fixed breeding season. The effects of sex, number of lambs per lambing, month and year of lambing were determined for weights at birth, 30, 120 and 210 days of age as well as lambing interval and age at first lambing using analysis of variance procedures in the SAS program. Heritability, repeatability as well as genetic and phenotypic correlations for the Morada Nova sheep in the herd were estimated using MTDFREML. The generation interval was 952 days, with a mean litter size of 1.25 lambs. Lambings were distributed throughout the year, but 77% occurred between March and September, indicating a possible influence of day length or food availability on reproductive traits. Direct heritabilities for birth weight, weight at 30, 120 and 210 days were, respectively, 0.15, 0.11, 0.07, and 0.21 for Morada Nova sheep. The correlations between these traits were positive (0.19 at 0.64). The heritability for lambing interval was 0.17 and 0.93 for number of lambs per litter. The results indicate that the breed and birth weight were highly significant for all weights studied. Lambing number and birth month affect all the traits examined.

Nitrogênio da biomassa microbiana em solo cultivado com soja, sob diferentes sistemas de manejo, nos Cerrados

The aim of this study was to quantify soil microbial biomass carbon in a soybean crop under different soil management systems: no-tillage, single harrowing, subsoiling and two harrowing, on a clay Red-Yellow Latossol in the Cerrado region. Soils were studied at five depths: 0-5, 5-10, 10-20, 20-30 and 30-40 cm. Four periods were observed: before soil preparation; 30 days after germination; flowering stage and after harvesting soybean plants. The same measurements were taken under the same conditions in an area of native cerrado vegetation, adjacent to the experiment (Cerrado sensu strictu). Subsoiling showed highest carbon values 30 days after germination (865.7 mg kg -1 of soil). This was reduced to less than 10% (80.3 mg kg -1 ) at flowering. The carbon values were more stable in the no-tillage system, mainly in the 0-20 cm layer. The layers 0-5 cm and 5-10 cm showed significantly higher carbon values compared with other layers in most of the studied periods and depths. Subsoiling showed the lowest soil organic carbon level after soybean harvesting. Only in the system with subsoiling there was no significant correlation between the microbial carbon:organic carbon index and soil nutrients.

Curvas de crescimento de ovinos Bergamácia criados no Distrito Federal

Fifteen years of data from a flock of Bergamasca sheep weighed every two weeks was analyzed using non-linear methods to determine parameters of three growth curves (Brody , Richards and Logistic). The curve parameters were analyzed using Statistical Analysis System (SAS) procedures GLM and CORR to determine factors which influenced them and correlations between the parameters and weights at determined ages. Fixed effects in the model included lambing number, sex of lamb, type of birth and month and age of lambing. The management system is semi-extensive, with the sheep at pasture during the day and imprisoned at night to protect them against predators. Means of the parameters were: Richards; A = 50.024, B = 0.647, k = 0.003, M = 17.771 and R2= 0.838; Brody; A= 52.763, B=0.885, k=0.003, R2= 0.842; Logistic; A =47.894, B=-3.895, k=0.007 and R²= 0.840. The environment influenced the growth of sheep in the region of Brasilia. The Logistic curve estimated adult weights lower than the other curves but the actual weights were better correlated with those estimated by this curve. There was no difference between the curves in terms of R2, and the error mean square was higher for the Richards curve. The negative correlation between A and k indicates that early maturing animals were less likely to reach high mature weights, compared with late maturing ones. The recommended curve for adjusting growth curves in Bergamasca sheep is the Logistic curve.

Use of heat tolerance traits in discriminating between groups of sheep in central Brazil

The animal and its environment make up an integrated system, where each acts on the other. Tropical regions are characterized by high levels of solar radiation and environmental temperature which may adversely affect animal production. This study carries out a multivariate analysis of physical and physiological traits in sheep in the Federal District of Brazil to test the ability to separate groups of animals and determine which traits are most important in the adaptation of animal to heat stress. The variables studied included coat thickness, number and length of hairs, pigmentation of the skin and coat, number of sweat glands as well as heart and respiratory rates, rectal and skin temperatures, sweating rate, and blood parameters. Five groups of ten animals were used depending on breed (Bergamasca, crossbred, or Santa Inês) or coat color (Santa Inês—brown, white, and black). The data underwent multivariate statistical analyses including cluster, discriminate, and canonical, using Statistical Analysis System—SAS®. The tree diagram showed clear distances between groups studied and canonical analysis was able to separate individuals in groups, especially Bergamasca and white Santa Inês. The canonical correlation redundancy analysis showed that coat reflectance as well as hair length and number of hairs per unit area were the most useful in explaining changes in physiological traits. Skin and coat traits such as hair length, coat reflectance, percentage of epithelial area occupied by sweat glands, skin reflectance and thickness, as well as heart and breathing rates were the most important in separating these groups.

Caracterização morfológica de eqüinos da raça Campeiro

Data was available on 498 horses registered by the Brazilian Association of Campeiro Horse Breeders. This included individual data on 16 linear traits [shoulder height (SH), mid back height (MBH), withers height (WH), back height (BH), head length (HL), neck length (NL), back length (BL), shoulder length (SL), hip length (HiL), body length (BOL), head width (HW), chest width (CW), hip width (HIW), chest circumference (CC), cannon bone circumference (CBC)], space under horse (SUH), coat color, temperament and nine subjective traits taken at registration. Body indices and weight were calculated from standard formulae where pectoral index (PI)= WH/SUH, dactyl-thoracic index (DTI), weight (BW), length index (LI), body index (BI), thorax index (TI), conformation index (CI), work index 1 (WI1) and work index 2 (WI2), compact index 1 (COI1) and compact index 2 (COI2). The effect of sex of animal, month, age and year of registration as well as coat color on the measurements was carried out using SAS® (Statistical Analysis System). The Campeiro horse is well proportioned with WH (1.46 m) slightly higher than SH. It is an animal that is between saddle and light traction, with a mean weight 419.96 kg, and medium length. WI1 and WI2 show that it can support 117.16 kg at a trot or gallop and a maximum weight of 198.76 kg at a fast walk. Variance coefficients varied widely but low measures predominated. Sex and coat color were not important sources of variation for measurements and indices. Month of registration influenced CC, CP, CD, CE, LP, LA, PT, PC and most indices. Year of registration did not influence AC, AD, ACost, CC, LP and PT, but was significant for the other linear measures and only for IT in the indices. Age influenced ACost, CD, LC, LP, LA, PT and most indices. The most popular coat color was chestnut followed by bay and dark grey.