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Biomedical subjects

P M Hocking

Publications and source records attributed to P M Hocking.

90 records · Page 5Linked to original sources
PubMed1991

Histopathology of antitrochanteric degeneration in adult female turkeys of four strains of different mature size.

The left and right antitrochanters of 80 female turkeys of four strains were examined for histopathological changes at sexual maturity. Ten birds of each strain were fed ad libitum and 10 restricted to achieve 0.6 of the bodyweight of the ad libitum fed birds at 24 weeks old when the birds were photostimulated. Bodyweights at sexual maturity (28 to 31 weeks) for the four strains were 5.4, 6.5, 7.6 and 13.2 kg for restricted and 7.5, 9.0, 11.1 and 17.1 kg for ad libitum fed birds. The prevalence and severity of cartilage change increased with mature size and was lower in restricted turkeys then in turkeys fed ad libitum. The results showed that abnormal cartilage changes forming the basis of clinical disease occur in females. The prevalence and severity of lesions were directly related to bodyweight and were not limited to particular genotypes. Lesions were more severe in the centre of the antitrochanter, possibly because of forces exerted by the trochanter. Concentrations of basophilic cells in the hyaline cartilage were associated with the increased prevalence and severity of lesions in large turkeys and may be of significance in the development of osteochondrotic lesions in the antitrochanter.

Animals↗
PubMed1991

Assessment of pain associated with degenerative hip disorders in adult male turkeys.

The extent to which degenerative hip disorders in adult male turkeys result in pain was investigated in a two-period crossover experiment. The birds in six pens received daily injections of an anti-inflammatory steroid (betamethasone) during week 1 and control injections of physiological saline in week 3. The turkeys in the other six pens received saline in week 1 and steroid in week 3. Behavioural observations of the birds during weeks 1 and 3 revealed that the steroid treatment resulted in more spontaneous activity. The steroid-treated birds also showed speedier movement in a sexual activity test in weeks 1 and 3. Post mortem examination revealed that all the turkeys were suffering from degenerative hip disorders. It is concluded that degenerative hip disorders in adult male turkeys result in a state of chronic pain which inhibits spontaneous activity and sexual activity.

Animals↗
PubMed1991

Effects of controlling body weight on the semen production of large white turkey males.

1. The consequences of limiting body weight gain during rearing on subsequent semen production and quality of Large White turkey males were assessed in a factorial experiment comparing ad libitum or restricted feeding in two periods (6 to 18 and 19 to 54 weeks of age). 2. The proportion of males giving semen, semen yields and concentrations of spermatozoa, and the incidence of unstable hock joints, were lower in males severely restricted from 6 to 18 weeks of age. 3. The best performance was from males that were reared on ad libitum feeding and fed 0.85 of ad libitum food consumption from 19 to 54 weeks of age.

Analysis of Variance↗
PubMed1990

Effects of interactions between photostimulation, dietary restriction and dietary maize oil dilution on plasma LH and ovarian and oviduct weights in broiler breeder females during rearing.

1. The response of the reproductive system to photostimulation was investigated during the rearing period in dwarf broiler breeder females maintained from hatch on 8 h light/d. The effect of increased body fat on this response was investigated. Body fat was increased by diluting the diet with maize oil. 2. A significant increase in plasma luteinising hormone (LH) was observed 4 d after photostimulation with 20 h light/d at 3 and 15 weeks of age in birds fed the restricted diet alone and at 3, 7, 11, 15 and 19 weeks of age in birds fed the restricted diet diluted with maize oil. 3. Increases in ovarian weight were observed two weeks after photostimulation at 15 weeks of age in birds fed the restricted diet alone and at 7, 11 and 15 weeks of age in birds fed the restricted diet diluted with maize oil. Increases in oviduct weight were seen after photostimulation at 11, 15 and 19 weeks of age in both dietary treatment groups; however, a larger increase in oviduct weight was seen at 15 and 19 weeks of age in birds fed the restricted diet diluted with maize oil. 4. In a second experiment, the dilution of a diet fed ad libitum with maize oil significantly increased body fat content and the baseline concentration of LH but did not enhance the response of the reproductive system to photostimulation. 5. Baseline plasma LH concentrations were lower in birds fed ad libitum than in those fed a restricted diet. 6. It is concluded that the neuroendocrine pathways involved in the transmission of photoperiodic information are functional at 3 weeks of age. The function of the components of the hypothalamo-pituitary complex which control reproductive activity is enhanced when a restricted diet diluted with maize oil is fed.

Animals↗
PubMed1990

Assessment of the effects of separate sex feeding on the welfare and productivity of broiler breeder females.

1. The welfare and productivity of female broiler breeders were studied in pens containing 15 females and 1 male where the sexes were fed together or separately by means of a grid with 40 mm spaces over the female feeders. 2. Average head width did not increase after 25 weeks of age. 3. The rate of lay was lower in separate compared with mixed-sex-fed pens but egg weight was similar. 4. The incidence of swollen heads and beak lesions was higher and feather loss and rate of food intake was lower in separate compared with mixed-sex-fed pens. 5. It was concluded that the grid spaces should be 42 mm wide to avoid adverse effects on welfare and productivity.

Animal Husbandry↗
PubMed1990

The relationships between dietary crude protein, body weight, and fertility in naturally mated broiler breeder males.

1. Naturally mated male broiler breeders were fed to achieve five levels of body weight gain on a high (160 g crude protein (CP)/kg) or low (110 g CP/kg) protein diet. Males were separately fed in 9 of the experimental treatments and fed with the females in the other. 2. There was an optimum body weight for maximum fertility which changed with age. The best fertility was shown by males weighing 3.2 kg at 26 weeks rising to 4.0 kg at 60 weeks of age. 3. The low protein diet was associated with higher fertility, particularly during the latter part of the breeding period (49-60 weeks). 4. Head width reached a plateau after 26 weeks of age and was 1 mm greater in males weighing more than 5 kg compared with males weighing 3 to 4 kg at 60 weeks of age.

Animal Feed↗
PubMed1989

Control of the development of the ovarian follicular hierarchy in broiler breeder pullets by food restriction during rearing.

1. The increase in the numbers of yellow and of white ovarian follicles was studied from 10 weeks of age to sexual maturity in broiler breeder pullets fed ad libitum and on a restricted intake. The growth of follicles greater than 1 mm diameter commenced at 14 to 16 weeks of age in ad libitum birds and at 22 to 24 weeks in those which were restricted. 2. In a second experiment, groups of birds restricted from 4 d of age were transferred to ad libitum feeding at 2-week intervals and examined at first egg. The numbers of yellow follicles at first egg were not affected by restriction to 14 weeks of age but, thereafter, declined linearly with time on restriction. 3. In the second experiment there were no comparable responses in the numbers of white follicles or in the rates of atresia. 4. Food restriction to 22 weeks of age produced about half the response in numbers of yellow follicles as restriction continued to point of lay (27 to 32 weeks of age). In practical situations, the results suggest that food intake should be restricted up to the onset of lay and then increased in relation to the rise in egg production. 5. Atresia was greatest in white follicles 3.15 to 6.30 mm diameter and was less outside this range.

Animals↗
PubMed1989

Musculo-skeletal lesions in adult male broiler breeder fowls and their relationships with body weight and fertility at 60 weeks of age.

1. Males from three broiler breeder experiments were examined to determine the incidence of musculo-skeletal lesions (destructive cartilage loss, dyschondroplasia and its sequelae, ruptured tendons and ligaments) in birds culled for low fertility and in males surviving to the end of the breeding period. Relationships with body weight and fertility were studied. 2. The incidence of musculo-skeletal lesions in males culled for low fertility was high. 3. In two experiments, high body weights at termination of the breeding period were associated with a raised incidence of musculo-skeletal lesions and lowered fertility. 4. The results support the hypothesis that lack of control of male body weight gain per se is an important cause of declining fertility with age in broiler breeder flocks. There was no evidence that males were obese.

Aging↗
PubMed1988

Effects of age and of early lighting on ovarian function in breeding turkeys.

1. Yellow follicle numbers and production of defective egg shells were greater in the early part of the laying period in conventionally-reared turkeys photostimulated at 24 rather than 30 weeks of age. 2. The number of yellow follicles declined with age and were similar in both groups at 40 weeks of age. 3. At 55 weeks of age more birds photostimulated at 24 weeks were out of lay and birds in lay had fewer yellow follicles and more atresia compared with turkeys photostimulated at 30 weeks of age. 4. The numbers of white follicles in the 1 to less than 2 mm size were similar in the two groups at each age. The proportion of white follicles which were atretic was negatively related to the number of yellow follicles, particularly in follicles 5 to less than 8 mm diameter.

Age Factors↗
PubMed1988

Factors affecting length of herdlife in purebred and crossbred dairy cattle.

The proportional hazards model with censoring was used to assess the effects of breeding value, disease, calving, size, and udder and lactation traits on length of herdlife of 3881 heifers in five herds. Data were recorded over 10 yr from three lines: a Holstein line, an Ayrshire-based line, and a crossbred line. Influences on survival were assessed from data collected at birth, 34, 50, and 82 wk, first freshening, and at 112 and 308 d postpartum. Median estimated herdlife (age at 50% culling) was 3.9 yr for animals alive at first freshening and increased to 4.3 yr for those that completed a first lactation (308 d postpartum). Herds differed greatly in the pattern of culling after freshening. Crossbred females had 21 wk longer median estimated herdlife than the mean of the purelines at 308 d postpartum. Individual milk yield was positively associated with longevity and had the greatest impact on length of herdlife. Abortion and fertility measured as days to last insemination were negatively associated with length of herdlife. Large heifers tended to have increased longevity. High feed intake postpartum was associated with reduced length of herdlife. Objective measures of conformation, which included measurements of the udder, were not important in determining herdlife.

Animals↗
PubMed1987

Ovarian follicular structure of White Leghorns fed ad libitum and dwarf and normal broiler breeders fed ad libitum or restricted until point of lay.

1. Yellow follicle numbers when the first egg was laid were 6.3, 9.0 and 12.4 for ad libitum reared Leghorns, sex-linked Dwarf (AL Dwarf) and Normal broiler breeders respectively. Multiple ovulation resulted in low egg production and a high proportion of defective egg shells in AL Dwarf and Normal broiler breeders during early lay. 2. Restricting the growth of broiler breeders during rearing by restricting food intake (R Dwarfs) reduced the number of yellow follicles to 6.8 and increased the rate of lay. 3. Atretic yellow follicles were common among broiler breeders but not in Leghorns or R Dwarfs when the first egg was laid. 4. Poor egg production in older broiler breeders was caused by birds with few or no developing yellow follicles, atresia in yellow follicles and the continued occurrence of multiple ovulations. 5. There was no relationship between the number of yellow follicles and the number of white follicles less than 5 mm diameter but atresia in white follicles 2 to less than 5 mm was negatively related to the number of yellow follicles. 7. No relationship was observed between abdominal fat weight and yellow follicle number, though birds which ate more had more yellow follicles. 8. The sex-linked dwarfing gene dw was associated with increased atresia among the white follicles and low numbers of yellow follicles compared with the Normal DW broiler breeder genotype.

Animals↗
PubMed1987

Observations on the size of the follicular hierarchy in the turkey hen and a case of arrested follicular growth.

1. The phase of rapid development of ovarian follicles in turkeys fed ad libitum or given a restricted allocation of food from 6 to 30 weeks of age was determined by feeding a fat soluble dye and counting the number of rings of dye in the yolks of laid eggs. 2. The duration of rapid growth was similar in ad libitum and restricted birds and averaged 11.6 d. The maximum number of yellow follicles greater than 8 mm expected in the hierarchy of the turkey hen is 9 to 10 compared with 6 to 7 in the chicken. 3. Discontinuous growth was observed in a series of follicles from one bird. This is believed to be the first report of arrested follicular growth in the turkey.

Animals↗
PubMed1986

Chronic orthopaedic disease in adult male broiler breeding fowls.

An assessment has been made of spontaneous orthopaedic disease in 100 male broiler breeding fowls aged between 51 and 62 weeks. Lesions were identified in the pelvic limbs of 92 birds, 85 of which showed total or partial rupture of ligaments or tendons. Total ligament or tendon failure was identified at one or more skeletal sites in 54 birds. In two cases, avulsion of the femoral origin of the cranial tibial muscle had occurred. Other findings included degenerative changes in a number of joints but there was no correlation with ligament derangement. Partial or total detachment of the femoral head occurred in 16 birds. The primary lesion was disturbed endochondral ossification and, once detached, the femoral head normally became necrotic. In the reparative phase, 'creeping substitution' was identified.

Animals↗
PubMed1985

Genetic variation in body size, composition, temperature, and feed intake in mature chickens.

Genetic variation for more than 40 traits was assessed in 26 stocks of mature chickens reared together and fed ad libitum from hatching to slaughter at 507 days of age. There was greater genetic variation among males than among females. The intraclass correlation, t, was high (greater than .75) for measures of size and weight and moderate (.20 to .60) for most other traits (P less than .05) including a measure of lean distribution (.37). Three main categories of stocks were studied, viz. outbred Leghorns, medium-sized stocks, and contemporary heavy meat chickens. Differences in lean distribution were not associated with category, but differences of 40 to 50 g/kg lean in the breast of some stocks may be caused by a single gene. Lean:bone ratios were similar in medium and heavy stocks but were greater (P less than .05) in heavy meat-types compared with outbred Leghorns. Bone density was higher (P less than .01) in females compared with males and in outbred Leghorns compared with heavier stocks (P less than .01). Heavy meat-type males were leaner (P less than .01) and had proportionately less fat in the abdominal cavity than outbred Leghorns. Carcass fatness was similar among stocks of females, but abdominal fat was lower in Leghorns selected for high egg production compared with unselected Leghorns (P less than .05) and heavy stocks (P less than .001). One resistant and two Marek's disease-susceptible stocks were replicated in a specific pathogen-free (SPF) environment. Spleen weight was larger (P less than .001) in the conventional environment. Females were relatively smaller (P less than .05) than males in the conventional environment. Body temperature (t = .25, P less than .05) and feed intake were assessed in males. Heavy meat birds had a lower (P less than .01) body temperature than outbred Leghorns and medium-sized stocks. Differences among stocks for feed intake (t = .77) were significant (P less than .05); however, they were greatly reduced when feed intake was expressed as g/kg liveweight (LW) (t = .49) or g/kg LW.75 (t = .25). Outbred Leghorns ate less in absolute terms but significantly more (P less than .01) as a proportion of LW or LW.75 than the medium and heavy lines.

Animals↗
PubMedDate not supplied

Evaluation of a protocol for determining the effectiveness of pretreatment with local analgesics for reducing experimentally induced articular pain in domestic fowl.

An experimental paradigm based on the microcrystalline sodium urate-induced arthritis model was developed for determining the effectiveness and optimum dose of drugs with potential local analgesic properties for the diagnosis and alleviation of musculoskeletal pain in birds. The optimum intra-articular injection of sodium urate was 6 mg in 0.2 ml diluent in 12-week-old male domestic fowl of 1.5 kg live weight. The response criteria were changes in behavioural profiles over 60 minutes commencing one hour after intra-articular injection. The testing system was used to determine the optimum rate of intra-articular application of the local anaesthetic bupivacaine hydrochloride. The behavioural profile of treated birds was restored to that of the controls at a minimal injection of 3 mg in 0.3 ml saline. It was concluded that the optimum intra-articular dose of bupivacaine for the treatment of musculoskeletal pain in the domestic fowl was 3 mg bupivacaine in 0.3 ml saline.

Anesthetics, Local↗
PubMedDate not supplied

Comparative development of antitrochanteric disease in male and female turkeys of a traditional line and a contemporary sire-line fed ad libitum or with restricted quantities of food.

The prevalence of musculoskeletal disease at eight, 16, 24, 34, 44 and 54 weeks of age in male and female turkeys was determined by dissecting 688 limbs from traditional lines and sire-line turkeys fed to achieve different bodyweights. Traditional turkeys were fed ad libitum and sire-line turkeys were fed ad libitum or restricted to 0.5 during rearing and subsequently to 0.8 of ad libitum-fed bodyweight of birds of the same strain and sex. A group of male sire-line turkeys was also fed ad libitum to 18 weeks and 0.8 of ad libitum thereafter. Lameness during the rearing period was usually associated with joint infection. Ruptured ligaments were an occasional finding in sire-line turkeys before sexual maturity. The major finding at 34, 44 and 54 weeks of age was degeneration of the antitrochanter in both sexes of the sire-line. The prevalence and severity of disease increased with age but was not generally associated with lameness. Antitrochanteric degeneration in the sire-line was diminished by decreasing bodyweight through food restriction. Antitrochanteric degeneration did not occur in traditional turkeys.

Animals↗