Sexual performance of rams as determined by maturation and sexual experience

The purpose of this study was to compare the sexual performance of rams that differed in age (maturation) and sexual experience. Twenty-four ram lambs (8 mo of age) and 21 rams (20 mo of age) were individually exposed to four females in hormonally induced estrus for 30 min on five occasions, 7 d apart. Half (12) the ram lambs and nine of the yearlings were sexually naive at the start of testing (had been denied access to females since weaning); the remaining males were sexually experienced. The sexual performance of the virgin rams was poorer during the initial exposure to females than in subsequent tests, whereas the sexual behavior of the sexually experienced males did not change over the days of testing. Sexually naive ram lambs and rams exhibited an improvement in sexual performance between Tests 1 and 2; during Test 3 to 5 the sexual performance (ejaculations per test) of sexually naive and experienced rams was similar. The only effects of age (maturation) on sexual performance during the last three test days were a higher frequency of mounts without ejaculation plus mount attempts (P less than .03) and a greater number of mount interactions per ejaculation (P less than .02) by ram lambs. In conclusion, one or two relatively brief exposures to estrous females can bring the sexual performance of virgin rams up to levels comparable to that of experienced males. Also, ram lambs in good condition exhibit acceptable levels of sexual performance.     

Development of sexual and aggressive behaviors in Hereford bulls

The purpose of this study was to describe maturation-related changes in the sexual and aggressive behaviors of Hereford bulls. Two groups of 13 and 14 bulls, respectively, were tested for sexual and aggressive behaviors every 3 mo from 3 to 24 mo of age. At 3 and 6 mo of age, the bulls were exposed, as groups, to two estrous females, whereas at 9, 12, 15, 18, 21, and 24 mo these bulls were tested under each of the following several treatment conditions: 1) individual tests (single males were exposed to single females), 2) small-group tests (three or four bulls:three females), 3) large-group tests (13 or 14 bulls:3 females), and 4) male-only tests (13 or 14 bulls were placed in the test arena in the absence of females). Most bulls consistently mounted females by 9 mo of age. Twenty-one of the 27 bulls (78%) attained their first ejaculation at either 12 or 15 mo of age. The frequency of mounting without ejaculation was greatest in large-group tests at 12 mo of age, and ejaculation frequency peaked at 18 mo. The incidence of male-male mounting in large-group tests (with females) did not appreciably change from 3 to 24 mo, whereas male-male mounting in male-only tests was greatest at 9 and 24 mo. We conclude that sexual performance data obtained in serving capacity tests administered to yearling bulls before 18 mo of age may underestimate the mating potential of certain individuals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Disruption of the caudal component of the reciprocal apparatus in two horses

Two horses became acutely lame following a fall during strenuous exercise and were diagnosed as having disruption of the caudal component of the reciprocal apparatus. Clinical signs consisted of lameness of the right pelvic limb, characterized by flexion of the hock and simultaneous extension of the stifle. Radiography revealed an avulsion fracture from the supracondylar tuberosity and fossa of the distal portion of the femur in one horse. Clinical and radiographic findings indicated avulsion of the lateral origin of the gastrocnemius and superficial digital flexor muscles. Treatment consisted of stall rest, limb immobilization, and phenylbutazone administration. One horse recovered to soundness and the other deteriorated and was euthanatized.     

Mass selection for increased 200-day weight in a closed line of Landrace pigs

Mass selection for increased weight at 200 d of age was conducted for six generations in a line of Landrace pigs. In the select line, the heaviest nine boars and 18 gilts were selected from each generation to produce the subsequent generation. A contemporaneous control line was maintained by randomly selecting a son from each sire and a daughter from each dam to attain a line size of five boars and 10 gilts. Inbreeding coefficients averaged .182 and .191 for the select- and control-line pigs and .150 and .162 for the select- and control-line dams, respectively, in the sixth generation. The 200-d weights and ultrasound backfat thickness data were collected from 1,022 pigs of 2,181 pigs farrowed. These pigs were sired by 92 boars and out of 210 sows. The generation interval was 13 mo. Twelve traits were studied: weights at birth and at 21, 35, 70, 154, and 200 d of age; daily gains from birth to 35 d, 35 to 70 d, 70 to 154 d, and 154 to 200 d; ultrasound backfat thickness at 200 d; and ultrasound backfat thickness adjusted for 200-d weight. Total weighted cumulative selection differential for 200-d weight was 88.7 kg. Realized heritability for 200-d weight was .26 +/- .08 with an average response of 4.2 +/- 1.3 kg/generation. Correlated responses resulted in increases for all weights and daily gains evaluated. Although ultrasound backfat thickness at 200 d increased in the select line compared to the control line, it was not altered by selection for 200-d weight when adjusted for 200-d weight.     

Serodiagnosis of Lyme disease in UK dogs

Lyme disease is a chronic, multisystemic, inflammatory disorder of man and animals associated with infection by the tick-borne spirochaete, Borrelia burgdorferi. Lyme disease was recently reported for the first time in a dog in the UK (May and others 1990). Using an enzyme-linked immunosorbent assay (ELISA), we have performed a serological survey to investigate the prevalence of antibodies to B burgdorferi in UK dogs. The survey has shown that dogs from many areas in the UK have serum antibodies to B burgdorferi, that the presence of serum antibodies is associated with known exposure to ticks and that some dogs seropositive for B burgdorferi have clinical signs consistent with Lyme disease. High levels of serum anti-Borrelia antibodies are not diagnostic for canine Lyme disease, but, in association with appropriate clinical signs, they help to confirm the diagnosis in suspected cases.     

Genetic diversity of Bangladeshi native chickens based on complete sequence of mitochondrial DNA D-loop region

ABSTRACT

1. The aim of this study was to explore genetic diversity and possible origin of Bangladeshi (BD) native chickens. The complete mtDNA D-loop region was sequenced in 60 chickens representing five populations; naked neck, full feathered, Aseel, Hilly and autosomal dwarf. The 61 reference sequences representing different domestic chicken clades in China, India, Laos, Indonesia, Myanmar, and other Eurasian regions were included. The mtDNA D-loop sequence polymorphism and maternal origin of five BD populations were analysed.

2. A total of 35 polymorphic sites, and 21 haplotypes were detected in 60 mtDNA D-loop sequences. The haplotype and nucleotide diversity of the five populations were 0.921 ± 0.018 and 0.0061 ± 0.0019, respectively. Both mtDNA network and phylogenetic analysis indicated four clades (four haplogroups) in BD populations (21 haplotypes) along with 61 reference haplotypes. Clade E contained the most individuals (20) and haplotypes (11) of BD chickens, followed by clade D (17, 6), clade C (12, 2) and clade F (11, 2), respectively.

3. The higher number of unique haplotypes found in Yunnan, China, suggested that the origin of BD chickens was in this region. The haplotypes from different haplogroups were introduced in Bangladeshi chickens from India, China and Myanmar. The phylogenetic tree showed a close relationship of BD chickens with the clusters from India, China, Myanmar and Laos, and indicated the dispersion of BD chickens from these sources. The phylogenetic information revealed high genetic diversity of BD chickens because of their origin from different lineages with high genetic variation and distance, which was determined from four cluster and neighbour-joining trees.

4. In conclusion, BD populations had high genetic diversity. The mtDNA network profiles and phylogenetic trees showed multiple maternal origins of BD chickens from India, China, Myanmar and Laos.     

Investigation into intraoral approach for nerve block injection at the mental foramen in the horse

Invasive dental procedures performed in the standing, sedated horse are facilitated by local and regional anaesthesia. The traditional transcutaneous approach to the mental foramen is used to desensitise the incisive region including the mandibular incisors, but is not well tolerated by many sedated patients. In this study, a new, intraoral needle insertion technique for nerve block at the mental foramen was investigated. In 15 equine cadaver heads and two live horses, computed tomography (CT) was used to verify Tuohy needle placement into each mental foramen using an intraoral technique. Varying volumes of contrast medium (3, 6, 10 mL) were injected into the mandibular canal with and without digital occlusion of the mental foramen. The distance of retrograde flow was measured. Additionally, measurements were taken to determine the position of the mental foramen within the interdental space. Correct placement of Tuohy needles and injection of contrast medium into the mandibular canal using an intraoral approach at the mental foramen was achieved in all injections. Retrograde flow of contrast medium was accomplished with all volumes, regardless of occlusion. Although not statistically significant, the 10 mL group appeared to have a greater distance of flow. The needle insertion technique described here appears to be a potential alternative to traditional transcutaneous approaches to mental nerve block for procedures involving the incisive region. In addition, it was found that 79% of the mandibular canals injected with 10 mL of contrast medium had retrograde flow to the position of PM4, suggesting this method may be a useful alternative technique for nerve block for the more rostrally located cheek teeth. The location of the mental foramen was consistently found in the distal third of the interdental space (approximately 60–80% of the distance between the distal aspect of the lateral corner incisor and the mesial aspect of the second premolar).