Groups Of Bulls Research Articles

The Effect of Various Concentrations of Taurine during In vitro Fertilization on the Development of Bovine Embryos Fertilized with Spermatozoa from Three Different Bulls

We investigated the effect of various concentrations of taurine during in vitro fertilization (IVF) on the embryonic development up to the blastocyst stage of bovine oocytes fertilized with three different Japanese Black bulls (Bull A, B and C). In vitro matured oocytes were fertilized with various concentrations of taurine (0, 1, 10, 50 and 100 mM) in the presence of 2.5 or 5.0 mM caffeine plus 25 μg/ml heparin (CH) for 6 hr or 100 μg/ml heparin (H) for 24±2 h. After IVF, the cleavage rates from the 2 to 16 cell stage determined at 3 days and the development rates up to the blastocyst stage determined at 7-8 days from the onset of IVF were assessed. Although the cleavage rates for the taurine concentration groups were not significantly increased in any of the three bulls in the CH groups, the development rates up to the blastocyst stage of the 50 mM taurine group of Bulls A and B, and of the 1 to 50 mM groups of Bull C were increased (p<0.05) compared to those of the control (0 mM taurine) groups. On the other hand, none of the bulls in the H groups showed any significant increase either in the cleavage rates or blastocyst formation rates in any taurine concentrations groups compared with those of the control groups. These results indicate that the addition of 50 mM taurine to a fertilization medium containing caffeine and heparin may stimulate embryonic development up to the blastocyst stage when fertilized with different bull semen.

Cholesterol concentration in seminal plasma as a predictive tool for quality semen evaluation

The aim of this study was to investigate the relationship between lipid composition of bovine serum and seminal plasma, seasonality, and semen quality. The experiment was carried out in two groups of Simmental breeding bulls: Group I (ages 2 to 4 yr) and Group II (ages 5 to 10 yr). Blood samples were collected from jugular vein, and bovine semen was sampled with an artificial vagina once per season. Serum concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triacylglycerols, nonesterified fatty acids (NEFAs), and lipoprotein electrophoretic patterns were determined. Seminal plasma concentrations of total cholesterol, HDL-C, and LDL-C were assayed. Serum concentration of triacylglycerols in young bulls was significantly higher in winter compared with that in autumn, whereas serum NEFA concentration was significantly higher in autumn compared with that in other seasons. Serum concentration of total cholesterol, LDL-C, and LDL lipoproteins in older bulls was significantly higher in winter than in spring. Seminal plasma concentration of total cholesterol in young bulls was significantly higher in spring compared with that in summer, whereas in older bulls it was significantly higher in winter compared with that in autumn samples. Sperm volume of both groups was significantly higher in summer compared with that in autumn and winter. Sperm motility in young bulls was lowest in summer and differed significantly from the values recorded in other seasons. The changes observed in seminal plasma cholesterol concentration were associated with extracellular lipid use and appeared to be applicable as a biochemical marker of sperm quality.

The influence of increasing population size and vegetation productivity on elephant distribution in the Kruger National Park

AbstractDecisions to reduce the impacts of large herbivores on biodiversity in protected areas are often based on controlling their numbers. However, numbers per se may not be the foremost consideration when managing impacts. This is because density‐related changes in distribution can also affect habitat utilization and hence, impact. In this study we tested whether changes in the distribution of African elephants are associated with increasing population size. We used spatially explicit count data collected during the dry seasons from 1998 to 2004 in South Africa's Kruger National Park. We did this at five spatial scales and in landscapes defined by vegetation, geology, climate and soils. We then investigated whether observed distributions and grid‐cell‐specific densities were associated with the remotely sensed Normalized Difference Vegetation Index (NDVI) as a measure of productivity and therefore food resource availability at the landscape scale. Consistent with density mediated changes, we found that elephant grid‐cell occupancy increased with population size, while grid‐cell‐specific density became less variable. In addition, the combined distribution of bull groups and breeding herds became less clumped with increasing population size. We further found that within landscapes elephants were present on grid‐cells with higher NDVI values, but that the influence of NDVI during the dry season on densities among landscapes may be weak. These results suggest that NDVI was more indicative of structural habitat choices such as woody vegetation than food availability per se. Our study highlights the need to consider factors other than population size alone when formulating management decisions to reduce large herbivore impacts on biodiversity in protected areas.

Breed variation in the chemical and fatty acid compositions of the Longissimus dorsi muscle in Czech Fleckvieh and Montbeliarde cattle

The aim of the experiment was to define the effect of cattle breed on chemical composition and fatty acid profile in intramuscular fat of Longissimus dorsi muscle of Montbeliarde (M) bulls and Czech Fleckvieh (CF) bulls fattened up to the same live weight and/or age. The pure-bred CF bulls (n = 20) and M bulls (n = 10) were divided into three groups: CF bulls — age (n = 10) fattened up to the age of 572 days; CF bulls — weight (n = 10) fattened up to the live weight of 706 kg and Montbeliarde bulls (n = 10) fattened up to the age of 572 days with live weight of 707 kg. All the bulls were loose-housed in pens with slatted floors from the age of 6 months (after a two-month preparation period) till slaughter and fed an identical feed ration (ad libitum intake of maize silage and a limited amount of concentrate). In both groups of CF bulls the content of C14:0, C14:1, C16:0 and C16:1 was significantly higher and C18:0 and C20:0 content was significantly lower compared to M bulls. However, the overall content of SFA, MUFA and PUFA was not significantly affected by breed. The values of Δ 9-desaturase (16) index were significantly higher in CF bulls than in M bulls. The chemical composition of the Longissimus dorsi muscle was not affected by breed.

Pre-freeze bull sperm head morphometry related to post-thaw fertility

Artificial insemination using cryopreserved semen is a common management tool of the contemporary livestock producer. The ability to determine post-thaw fertility from pre-freeze sperm function parameters would be of major benefit to producers. In this study computer-aided sperm head morphometry was used to determine whether there is any association between pre-freeze bull sperm head measurements and post-thaw non-return to oestrus rates. Sixteen commercial artificial insemination bulls were used for this study. Of the 16 bulls, eight had ≥69% non-return to oestrus rates while the remaining eight bulls had <69% non-return to oestrus rates, based on artificial insemination of cryopreserved semen from a minimum of 748 inseminations per bull. Microscope slides of extended or cryopreserved and thawed semen were prepared and stained by the MGZIN procedure. The morphometric dimensions for length, width, width/length, area and perimeter for a minimum of 200 sperm heads were analyzed from each slide by ASMA and the mean measurements and intra-analysis coefficients of variation (CV) recorded. The post-thaw non-return to oestrus rates for all bulls were correlated with pre-freeze measurements of width ( r = 0.53, P < 0.05), and the change in width/length after cryopreservation ( r = 0.61, P < 0.05). There were no significant differences in the mean pre-freeze or post-thaw sperm head measurements between the two groups. However, the mean post-thaw change in width/length was significantly ( P = 0.003) different between the groups. The mean post-thaw intra-analysis variability for width was significantly lower ( P = 0.03) in bulls with non-return to oestrus rates (NRR) ≥ 69%. Overall, the data suggests that pre-freeze and post-thaw bull sperm head morphometry measurements of individual bulls may have minimal predictive value of post-thaw fertility as determined by non-return to oestrus rates between groups of bulls with limited variance in non-return to oestrus rates. The clinical relationship of sperm head morphometry and fertility in bulls with a greater, clinically significant range of non-return to oestrus, remains to be studied.

Study of DNA integrity in somatic cells and spermatozoa by single-cell gel electrophoresis with silver-nitrate staining

In the present work, genome instability in human and bovine peripheral blood lymphocytes and spermatozoa was studied by the method of DNA microelectrophoresis with subsequent staining of single cells with silver nitrate. A comparative analysis of the types of damage to human and bovine lymphocytes and spermatozoa genomes was performed. In the group of healthy donors, the spontaneous frequency of DNA damage revealed by single cell DNA microelectrophoresis did not exceed 9% and amounted, on average, to 4.8 ± 1.2%. In studying the effect of the duration of cryoconservation on bovine spermatozoa, no significant changes were revealed between the group of bulls whose spermatozoa were stored for less than one year (3.1 ± 0.9%) and the group of animals whose spermatozoa were under conditions of cryoconservation for more than 20 years (4.3 ± 0.5%). From the obtained single-cell DNA microelectropheretic data on the types and frequencies of DNA damage, a conclusion was made regarding the possibility of using a light variant based on cell staining with silver nitrate for the detection of genome instability, not only in somatic, but also in reproductive, cells.

Estimation of bull live weight through thermographically measured body dimensions

Estimating the live weight of bulls by measurement of body dimensions with thermography and thermal image analysis was studied during progeny testing of the Simmental breed. The experimental group of bulls was measured seven times every 60 days from housing at the average age of 139 days (181 kg) till slaughtering (449 days, 594 kg). Each bull was weighed, manually measured and captured by the thermal camera. This device, together with the image analysis algorithm, proved to be a successful tool for estimating the wither height (Wh) and hip height (Hh) during all seven age classes. The SEE values for Wh decreased significantly during all weighing from 5.49 cm at day 139 to 1.11 cm at day 449 and from 4.99 to 1.76 cm for Hh, respectively. Two linear models for estimating current body weight at different ages were also developed on the basis of the long-term herd data of the Wh (BW1) and Hh (BW2) measurements. A statistically significant relationship ( P < 0.05) was found for all seven age classes, whereby the R adj 2 was varying with the age from 0.11 to 0.66 (BW1) and from 0.15 to 0.74 (BW2). Since the SEE values increased a little from 24.96 kg at day 139 to 33.59 kg at last weighing for the BW1 and from 21.76 to 32.69 kg for the BW2, both models expressed high accuracies. Therefore the thermal camera shows to be a useful tool in estimating live BW, which is of significant importance in reducing stress during progeny testing and beef production.

Solutions for elephant Loxodonta africana crop raiding in northern Botswana: moving away from symptomatic approaches

Conflict between people and elephants in Africa is widespread yet many solutions target the symptoms, rather than the underlying causes, of this conflict. To manage this conflict better the underlying causes of the problem need to be examined. Here we examine factors underlying spatial use by elephants and people along the Okavango Panhandle in Ngamiland, northern Botswana, to provide ways to address the causes of the conflict between elephants and people. We found that (1) elephant spatial use was a function of season, (2) spatial use did not differ between breeding herds and bull groups, (3) spatial use by elephants and people only overlapped significantly at night, during the dry season, (4) crop raiding by elephants was a function of season and social grouping, and (5) crop raiding by elephants had social and economic implications. Based on these results we suggest measures to manipulate elephant spatial use to reduce the causes of this conflict. We also reflect on present compensation measures for elephant crop damage and advocate that a more direct performance payment approach may benefit both the Botswana Government and local farmers.

Relationships Among Age, Body Weight, Scrotal Circumference, Semen Quality and Peripheral Testosterone and Estradiol Concentrations in Pubertal and Postpubertal Holstein Bulls

In the present study, the correlations among age, body weight, scrotal circumference (SC), semen quality and peripheral testosterone and estradiol-17beta (E(2)) concentrations were investigated in pubertal (n=5) and postpubertal (n=7) groups of Holstein bulls over a 6 week period. There were significant positive correlations (P<0.01) among age, body weight and SC in both groups, and similar significant correlations between sperm motility and SC in pubertal bulls (P<0.01) and between sperm concentration and SC in postpubertal bulls (P<0.05). The sperm motility after collection (P<0.05) and after freezing and thawing (P<0.01) of the postpubertal bulls correlated positively with the E(2) concentration. Estrogen may be important for the function of postpubertal bull testes, in which it may regulate spermatozoa motility in vivo.

Crossbred Bull Selection for Bigger Scrotum and Shorter Age at Puberty with Potentials for Better Quality Semen

Shortening age at puberty of crossbred breeding bull is an important issue in the tropics. This study aimed at selecting crossbred bulls at earliest possible age with bigger scrotum and potential for donating quality semen. One hundred and 31 pre-joining crossbred bulls of Central Artificial Insemination Laboratory, Saver, Dhaka were examined. The bulls being trained by seeing semen collection from mature bulls were allowed ejaculation into the artificial vagina at homosexual mount during a 20 min time at three occasions, every three months. Eighty one of 131 bulls produced at least one ejaculate during the study and their mean +/- SD age and scrotal circumference (SC) were 20.3 +/- 4.7 months and 28.2 +/-2.7 cm, respectively. Bulls' body weight, body condition score (BCS) and SC influenced the attainment of their puberty (p < 0.05). Bull's body weight had positive effects on scrotal circumference and ejaculate volume (p < 0.05). Scrotal circumference positively influenced the percentages of normal spermatozoa (p < 0.05). Scrotal skin-fold thickness negatively influenced the proportion of spermatozoa with normal head (p < 0.05). Based on age at first ejaculate and SC, 29.6% bulls (n = 24) were selected by cluster analysis. Selected bulls had mean +/- SD age 17.9 +/- 2.2 months, body weight 287.3 +/-48.6 kg, SC 30.5 +/- 1.5 cm, ejaculate volume 3.4 +/- 1.3 ml, sperm motility 50.8 +/- 17.2%, total spermatozoa per ejaculate 2541.9 +/- 1699.2 million and normal spermatozoa 81.5 +/-14.5%. The selected pubertal bull group was different from the unselected pubertal bulls at MANOVA (p < 0.0001). About 30% of pubertal crossbred bulls can be selected with shorter age and larger scrotum at puberty under conditions prevailed in Bangladesh.

Elephants and water provision: what are the management links?

ABSTRACTIn a recent paper we demonstrated that elephant bull groups and mixed herds exhibited spatial and resource segregation across the Kruger National Park. It was found, inter alia, that both bull groups and mixed herds occurred more frequently closer to rivers than expected if they were randomly distributed, but that only bull groups occurred more frequently closer to the artificial waterholes. Although Chamaillé‐Jammes et al. (2007) accepted these results, they disagreed with our interpretation regarding the potential effect that closure of artificial waterholes might have. Here we address some of the specific concerns expressed and provide a broader context regarding water provision and elephant management. Although water provision can influence elephant density and distribution, we argue that the effectiveness of surface‐water manipulation as a management tool will depend on (1) natural surface‐water availability, (2) forage quality, (3) elephant densities, (4) position of a population on its growth trajectory, and (5) management objectives. Even though elephants are water‐dependent, the effectiveness of water provision as a management tool will therefore be area‐ and population‐specific and will depend on management objectives.

Fibrotic lesions in the testis of bulls and relationship to semen quality

Ultrasonography of the testes was done in bulls at three locations in western Canada ( n = 325) and one in Argentina ( n = 387) to determine the prevalence of fibrotic lesions and to examine the relationship between fibrotic lesions and location, age, breed, right compared with left testes, testis size and semen quality. Fibrotic lesions were common in the testes of bulls raised under intensive rearing conditions in western Canada as well as in the more extensive rearing conditions of Argentina. Fibrotic lesions appeared as early as 5–6 months of age and the number of cases continued to increase until at least 12–14 months of age. The severity of lesions increased in some cases during this period; however, it appears that the development of lesions occurred during a finite period of pubertal development. It is unlikely that the prevalence of lesions is influenced by breed, right compared with left testes or testis size. The cause of the lesions is unknown, but there was an association between the development of fibrotic lesions and an outbreak of BRSV disease in Argentina in one group of bulls. There was some indication that during the active process that leads to fibrosis spermatogenesis is adversely affected; however, the presence of a large number of fibrotic lesions that may occupy as much as 50% of the testis parenchyma did not preclude the production of a greater percentage of sperm with normal morphology.

Landscape‐scale sexual segregation in the dry season distribution and resource utilization of elephants in Kruger National Park, South Africa

ABSTRACTThis study compared the dry season distribution of elephant bull groups and mixed herds and the resources driving these distributions within Kruger National Park, South Africa. It is important to understand what resources drive the distribution of elephants as this may be of relevance to understanding and managing their impact. It is also important to distinguish between resource use by bull groups and mixed herds because their impact on the habitat may differ. Our results indicated that sexual segregation, both in space and in resource selection, did occur in Kruger Park. Bulls roamed more widely in the park, and although their distribution and resource use overlapped with mixed herds, they also occurred in areas that mixed herds apparently did not, or could not, utilize in the dry season. This gave rise to areas used exclusively by bulls but no areas used exclusively by mixed herds. Lower collective feeding requirements as a result of smaller group size, wider habitat tolerance, and increased mobility as a result of bigger body size, as well as conflict avoidance with musth bulls in areas with mixed herds, might have been some of the reasons for bull groups roaming more widely and for the establishment of separate bull areas. Rivers were an important resource driving both the distribution of the mixed herds and bull groups, but with the mixed herds occurring closer to these resource hot spots than the bull groups. Tree cover proved important for mixed herds, probably because of the importance of shade and the higher nutritional requirements of the smaller‐sized cows and calves. Artificial waterholes might have opened up previously unutilized areas for bulls in the dry season, especially on the grassy basaltic plains in the north of the park. However, the distribution of the mixed herds suggested that they did not occur in higher densities in areas surrounding waterholes.

A Total Merit Selection Index for Ontario Organic Dairy Farmers

Organic standards require changes in management practices so that health, fertility, and overall fitness are more important than on conventional dairy farms and require different selection objectives. A survey involving 18 (40%) Ontario organic dairy farms was carried out to collect data on their production systems, breeding policies, and concerns. Compared with conventional farms, organic farms had lower milk production, lower replacement rate, higher somatic cell count, and a much higher rate of crossbreeding. Actual culling rate was 21%, and the main causes were fertility, mastitis, feet and legs, production, and old age. The major areas of concern expressed by organic dairy farmers were related to grazing traits, fertility, health, and longevity. An organic total merit index was developed based on the subjective scores for traits with a genetic evaluation in Canada. The relative weights of production to fitness traits (28:72) were substantially different from those in the Canadian Lifetime Profit Index (54:46), but similar to those used in conventional indices in Sweden and Denmark and in the Swiss organic index. The overall weight on health traits was 2.5 times higher in the organic index and, among fitness traits, the emphasis was substantially higher for lactation persistency, somatic cell score, and body capacity. Correlations between the organic index and Lifetime Profit Index were 0.88 for all bulls proven in Canada, 0.70 for the top 1,000, and 0.65 for the top 100, indicating that a different group of bulls would rank at the top of these 2 indices. When the top 100 bulls for either index were compared, those selected for the organic index were about 0.5 standard deviations lower for all yield traits, but were much better for body capacity and somatic cell score, and 0.25 standard deviations higher for herd life, feet and legs, udder conformation, and lactation persistency. Given the small population size, a separate breeding program for an organic management system is not viable in the foreseeable future. However, the organic index would allow producers to rank proven bulls in accordance with their perceived needs.

Use of large bulls to improve the body weight of local small sized buffalo

Eight Swamp buffalo bulls (4 large and 4 local small sized) and 240 buffalo cows (120 selected and 120 non-selected) were used to evaluate the effects of bull size and selected cows on body weight of calves. Experimental animals were allocated into 4 groups: T1- large sized bulls x selected cows (BSB+SC); T2 - large sized bulls x non-selected cows (BSB+NSC); T3 – local small sized bulls x selected cows (SSB+SC) and CT – local small sized bulls x non-selected cows (SSB+NSC) as a control group. Each bull was mated with 15 selected cows and 15 non-selected cows.Body weight of calves at birth, 3, 6, 12 and 24 months of ages was highest in calves of T1, then T2 and then T3 while the lowest weight was found in the CT group. Calf weight in the large sized bulls and selected cows group was higher by 10-15% than that of calves in the local small bulls and non-selected cows group at all ages. It is concluded that the use of large sized bulls for breeding increased body weight of calves. Using large bulls and selected buffalo cows was the best solution for improving the body weight of the local buffalo.

Need of reevaluation of the parameters of semen straws to be used in artificial insemination programs

In buffalo industry artificial insemination is being used in breeding programs of our country . It has limitations such us seasonality, difficult estrus detection and low pregnancy rates when compared with cattle. IATF programs using a single insemination show results from 10 to 50% pregnancy rate, little information is available about minimum requirements of spermatozoa for IA. The aim of this paper is to compare the pregnancy rates after using narual mating or frozen semen in a sincronization of ovulation program. This work were conducted in Pueblo Nuevo Cordoba Colombia in August during the breeding season of 2005-6. 99 multiparous crossbred females were used with 50 to 150 postpartum days. Body score condition of 3,5 to 4. All animals were palpated to exclude anatomical alterations. Ovsynch protocol for IATF reported by Baruselli (2000), they were allocated in two groups: Buffalo group, after the last GnRH analog injection 17 females were allocated with 5 bulls, and IATF Group 82 females were inseminated 16 hours later. The semen of 7 different buffalo bulls were used and evaluated and qualified as normal. Inseminations were performed by 3 different technicians. A blood sample was obtained 20 days after IA to determine pregnancy by determinations of P4 levels using chemiluminiscence, ≥1ng/ml were used as cut off value to determine pregnancy. Data were compared using Chi square test. 70% (12/17) females of the bull group and 29% (24/82) of IATF group were diagnosed us pregnant using P4, this difference were statistically significant (P≤0.001). Buffalo bulls mount all females. No statistical differences were found in pregnancy rates of the bulls used for IATF, from 12% to 37 %, one exceptional bull obtain 71%. As expected bulls have higher pregnancy rates than artificial insemination, the results obtained here allow researchers to evaluated semen quality, specially density to improve results IATF in buffaloes.

Multiple-Trait Multiple-Country Genetic Evaluations for Udder Health Traits

International genetic bull evaluations of somatic cell counts (SCC) from 8 different Holstein populations and clinical mastitis from 3 of these populations were inferred simultaneously using a multiple-trait–multiple-country evaluation (MT-MACE) model. This model considered effective independent weighting factors and multivariately deregressed national genetic evaluations for countries with multiple-trait national models. Predictions of genetic merit from MT-MACE and their reliabilities were compared with the corresponding results from 2 separate single-trait–multiple-country evaluations (ST-MACE) for different groups of bulls. The assumed heritabilities for clinical mastitis (h2 = 0.02 to 0.05) were substantially lower than the heritabilities for SCC (h2 = 0.08 to 0.27). The predictive ability of MT-MACE was essentially equal to or better than the predictive ability of ST-MACE for all country-trait combinations, but both methods yielded effectively unbiased and consistent consecutive predictions (correlation>0.93). Both sets of predictions also agreed well with future national genetic evaluations for bulls receiving additional daughter information (correlation>0.96), except for evaluations for which within-country correlations were utilized internationally, but not nationally (correlation = 0.86 to 0.97). The reliabilities for MT-MACE were essentially equal to or higher than reliabilities for ST-MACE, depending on the trait and group of bulls in question. Reliabilities increased most for young bulls, and for clinical mastitis in countries that did not use the within-country correlations with SCC in the national evaluation (up to a 23% increase in average reliability).

Effect of different levels and sources of zinc supplementation on quantitative and qualitative semen attributes and serum testosterone level in crossbred cattle (Bos indicus×Bos taurus) bulls

An experiment was conducted on 16 crossbred bulls (about 2 years of age, 316.2+/-0.77 kg average body weight), divided into groups I, II, III and IV to study the effect of different levels of Zn supplementation from inorganic and organic sources on semen quality. The animals in the first 3 groups were supplemented with 0, 35 and 70 ppm Zn from Zn sulfate, respectively and the animals in-group IV were supplemented with 35 ppm Zn as Zn propionate. Semen collection and evaluation was done in the first month (to assess semen quality at the start of the experiment) and 7th, 8th and 9th month of experimental feeding to evaluate the effect of supplemental Zn on semen attributes. We gave 6 months for Zn feeding, so that 3 sperm cycles of spermatogenesis had passed and the collected semen reflected the complete effect of Zn supplementation. Six ejaculates from each bull were collected and evaluated for semen quantitative (ejaculate volume, sperm concentration and sperm number per ejaculate) and qualitative characteristics (semen pH, mass motility, individual motility, sperm livability percent and abnormal sperm percent, percent intact acrosome, bovine cervical mucus penetration test, hypo-osmotic sperm swelling test) and activity of seminal plasma enzymes i.e., alkaline phosphatase, acid phosphatase, GOT and GPT. Testosterone level in the blood serum of crossbred bulls was also estimated. Mean values of semen quantitative and qualitative characteristics at the start of the experiment were statistically non significant (P > 0.05) in all the crossbred cattle bulls, however, there were statistically significant differences among the bulls of different groups after 6 months of zinc supplementation. Mean ejaculate volume (mL) was 2.37, 4.70, 5.86 and 6.38, respectively in groups I to IV, indicating a statistically significant (P < 0.05) higher semen volume in Zn-supplemented groups as compared to the control group of bulls. Similarly, sperm concentration (million.mL(-1)), live sperm (%) and motility (%) were significantly (P < 0.01) higher in Zn-supplemented groups as compared to the control group. The results of BCMPT and HOSST revealed a significant improvement in sperm functional ability in all the groups supplemented with Zn as compared to the control group. The activity of alkaline and acid phosphatase in seminal plasma was significantly (P < 0.05) higher in the Zn-supplemented groups, whereas GOT and GPT activities in seminal plasma were significantly (P < 0.05) lower in the Zn propionate supplemented group as compared to the control group. Testosterone concentration (ng.mL(-1)) in blood serum was significantly higher in animals of groups III and IV, as compared to control group. It may be concluded that Zn supplementation either in the inorganic or organic form in the diet of crossbred bulls improved the qualitative and quantitative attributes of semen; however, the number of sperm per ejaculate, mass motility and semen fertility test like bovine cervical mucus penetration was significantly higher in bulls given Zn in an organic form (Zn propionate) as compared to an inorganic form (Zn sulfate).

Quantification of the contact structure in a feral cattle population and its hypothetical effect on the transmission of bovine herpesvirus 1

The organisation of animal populations in social groupings may play a crucial role in the transmission of any infectious disease that requires close contact. The objective of this study was to quantify the contact structure of part of the Heck cattle population in a Dutch nature reserve and its hypothetical effect on the transmission of bovine herpesvirus 1 (BHV1). The contact structure was quantified by observing the number of different animals with whom contact was made (i.e. the number of contactees) within a fixed time period. Two types of behaviour sampling methods, namely focal sampling and scan sampling were used to observe the contact structure. In this study only those contacts between individuals were observed that were assumed to be a proxy measure of an at-risk event for BHV1-infection. Two reproduction ratios ( R), i.e. the average number of new cases caused by a typical infected individual, were estimated, one for the observed contact structure and another for a random mixing contact structure. The two reproduction ratios were then compared to study the hypothetical effect on BHV1 transmission. The overall number of contactees was highest during summer and lowest during winter-spring. The contact structure of the homogeneous population did differ significantly from a random mixing contact structure, resulting in that the variation in the number of contactees was higher than under random mixing. Bulls, young bulls and cows had the highest number of contactees during, respectively, summer, autumn and winter-spring. From the analysis of the contingency tables it was clear that contacts between animal types did not occur at random during summer and autumn. For example, during summer more contacts than expected occurred between bulls and cows. This heterogeneity at animal type level was taken into account in the calculation for R, which resulted for the observed contact structure in higher estimates for R than for the homogeneous population. When looking at heterogeneity at individual level it was found that during summer almost all individuals were observed together direct or indirect in the same group except for certain bull groups. During autumn and winter-spring almost all individuals were seen together in the same group when considering a long contact period of 14 days but the groups were fallen apart in smaller groups and solitary individuals for a short contact period of 5 days. It could be concluded that based on the observed contact structure transmission would be favoured most during summer.

Book review

The aim of this study was to analyse the consequences of selection on the development of muscle fibres in the semitendinosus muscle of two groups of Charolais bulls with a high or low muscle growth index. Muscle fibre kinetics were analysed during foetal life (110, 180, 210, 260 days of gestation) and after birth (3 weeks, 9, 15, 19 months). The weight, length and area of muscle were measured. The total number of fibres and muscle fibre area were calculated for each stage. The contractile properties of fibres were revealed by immunohistochemistry. Oxidative capacity of individual fibres was determined on serial sections stained for Succinate Dehydrogenase. Finally, whole muscle metabolic properties were measured on homogenates of muscle with analysis of the activity of Lactate Dehydrogenase (glycolytic) and Isocitrate Dehydrogenase (oxidative). The main results showed muscle hypertrophy in bulls with a high growth potential due to a higher total number of fibres (indicating hyperplasia). From the last trimester of gestation onwards, this is associated with particular contractile and metabolic properties, with mainly a higher proportion of IIX fibres (fast glycolytic). However, the delayed physiological maturity of these bulls induced a delay in the plasticity of muscle fibres after birth. Consequently, the effects of selection on growth rate on muscle properties are not evident at each stage.