Biomedical subjects

G W Robertson

Publications and source records attributed to G W Robertson.

At least 19 recordsLinked to original sources

PubMed2005

Effects of non-steroidal anti-inflammatory drugs on pain-related behaviour in a model of articular pain in the domestic fowl.

The optimum doses of carprofen, flunixin, ketoprofen and sodium salicylate for the treatment of inflammatory pain were determined in domestic fowl using the microcrystalline sodium urate model of articular pain. The response criteria were the changes in pain-related behaviour over 60 min commencing 1 h after an intra-articular injection of sodium urate and an intramuscular injection of a range of doses of each of the drugs. The minimum effective doses for carprofen, flunixin and ketoprofen, respectively, were 30, 3 and 12 mg kg(-1). The minimum dose for sodium salicylate ranged from 100 to 200 mg kg(-1) and did not fully restore normal behaviour.

Animals↗

PubMed2005

Limited effect of intense genetic selection for broiler traits on ovarian function and follicular sensitivity in broiler breeders at the onset of lay.

Female chicks from 6 pure lines of broiler breeders were obtained from international broiler breeder companies. The lines were from three female and two male lines and a relaxed selection line derived from one of the male lines (M2) and maintained without selection for 25 years (generations). Replicate groups from each line were reared in floor pens and fed ad libitum. An additional group of the M2 male line was feed restricted and housed in similar pens. Twenty birds from each group were photostimulated after housing them in individual cages at 14 weeks of age. Ovarian follicular dynamics and follicular sensitivity were determined after the onset of lay. Female lines had a greater proportion of atretic follicles and more groups of multiple follicles than male lines. Body weights, fatness and age at puberty were similar in male and female lines. The relaxed selection line had more abdominal fat than any of the selected lines and the ovary contained a similar number of normal yellow follicles as the selected male line. Feed restriction decreased body weight, the numbers of yellow follicles, multiple yellow follicles and the proportion of atretic yellow follicles, and increased the age at onset of lay. The response of ovarian follicles of three different sizes to exogenous gonadotrophin stimulation with PMSG was similar in small yellow follicles, 5 to 6 and 2 to 3 mm white follicles in a female line, a male line and its relaxed line fed ad libitum. The results suggest that the original lines from which modern male-line broiler stocks are derived had a relatively large number of yellow follicles and a high propensity for multiple ovulation at the onset of lay. Separate selection for different traits in male and female lines has not had a dramatic effect on ovarian function or sensitivity to gonadotrophin stimulation.

Aging↗

PubMed2003

Effects of dietary protein concentration and specific amino acids on body weight, body composition and feather growth in young turkeys.

1. Two randomised block factorial experiments were conducted to investigate the relationships between the effects of dietary crude protein and specific amino acid concentrations on the relative growth of the body and feathers of young turkeys. 2. Decreasing dietary crude protein concentration from 300 to 180 g/kg in experiment 1 reduced the body and breast muscle weights of a large male line of turkeys proportionally by 0.44 and 0.52 compared with 0.19 and 0.24 in a small traditional line. 3. Decreasing dietary crude protein concentration was associated with a maximum reduction in feather weight of 0.18 and 0.24 respectively in male line and traditional turkeys. The length of the feathers in the cranial region of the breast decreased from 26 to 19mm in the traditional line compared with an increase from 14 to 25 mm in male line turkeys. 4. Decreasing dietary crude protein concentration was associated with an increase in the fat content of the feather-free carcase. Male line turkeys had a higher carcase fat and lower feather dry matter content than the traditional turkeys. 5. It was concluded that dietary crude protein was preferentially partitioned to feather rather than muscle growth in the male line in contrast to a traditional line of turkeys in which the growth of feathers and muscle were affected equally. 6. In experiment 2, the amino acids arginine, valine, methionine and tyrosine were added separately to a common basal ration (180g CP/kg) to raise their concentration to that of the control ration (260 g CP/kg). Each ration was fed ad libitum to male line turkeys from 2 to 6 weeks of age. 7. Amino acid supplementation increased body and breast muscle weights. 8. Compared with the basal ration, tyrosine was associated with a reduction in feather weight whereas valine had no effect. Supplementation with arginine and methionine resulted in increased feather weights that were similar to that of the controls. 9. It was concluded that arginine and methionine were used preferentially and are essential for feather growth. Excess amino acids that are not required for feather growth such as tyrosine and valine were used for increased body growth and resulted in relatively poor feather cover. 10. The results suggest that feather growth was maintained as much as possible at the expense of body growth when the amino acid concentration of the ration was less than that required to maximise body and muscle weight gain in large male line turkeys.

Amino Acids↗

PubMed2002

Role of dietary calcium and available phosphorus in the aetiology of tibial dyschondroplasia in growing turkeys.

1. Large White male turkeys from a heavy commercial male-line were fed 16 diets containing 4 concentrations of calcium (6, 10, 14 and 18 g/kg) and available phosphorus (3, 5, 7 and 9 g/kg) in a 4 x 4 factorial experiment. There were three replicates (pens) of each treatment and the skeletal health, morphology and mineral status of 4 turkeys from each pen were assessed at 7, 10 and 13 weeks of age. 2. The prevalence of tibial dyschondroplasia increased after 7 weeks of age and was present in 50 and 71% of turkeys respectively at 10 and 13 weeks. The lesion was localised in the caudal aspect of the proximal tibiae. Dietary calcium and available phosphorus did not affect the prevalence of the lesion except in turkeys on the diet containing 6 g calcium/kg, where body weight and the incidence of tibial dyschondroplasia were low. 3. Histological investigation showed no evidence of rachitic changes. 4. Low dietary calcium was associated with lower tibial plateau angles at 10 and 13 weeks of age. Tibial torsion and the angle of rotation were not affected by dietary treatments or age. Tibial torsion and the angle of rotation were not affected by dietary treatments or age. 5. Increasing dietary calcium increased tibial radiodensity, cortical density and the widths of the cortex and proximal tibiotarsus. Radiodensities increased to 10 weeks and were significantly lower at 13 weeks of age. 6. Bone ash, calcium and phosphorus declined with age, particularly between 10 and 13 weeks, whereas bone calcium: phosphorus ratios were not affected by dietary treatment or age. 7. Dietary calcium was positively associated with blood calcium and calcium ion concentrations and was without effect on blood phosphorus. Available phosphorus was associated positively with increased blood phosphorus and lower calcium ion concentrations but had no effect on total calcium. Alkaline phosphatase activity was low at high concentrations of dietary calcium with low available phosphorus and there was higher activity on diets containing low calcium and high available phosphorus.

Age Factors↗

PubMed2002

Welfare assessment of broiler breeders that are food restricted after peak rate of lay.

1. Broiler breeder females were reared on one of three growth curves (ad libitum, conventional or modified restriction) and given rations containing a high or low concentration of crude protein. After the peak rate of lay they were fed ad libitum or a decreasing quantity of food in response to declining egg production. The welfare of the birds was assessed by determining the changes in indices of welfare at 36, 48 and 60 weeks of age. 2. Body weight increased rapidly in restricted birds fed ad libitum post-peak and water intake declined. 3. Post-peak food restriction was associated with a decrease in resting and increased drinking and spot-pecking activities. Birds that were food restricted during rearing spent more time foraging and spot-pecking at 36 and 48 but not 60 weeks of age. 4. Immune function increased with age but was not affected by the experimental treatments. The heterophil-lymphocyte ratio in birds fed ad libitum during rearing was numerically lower at 36 and higher at 48 and 60 weeks of age compared with restricted birds. 5. There was no effect of treatment on plasma corticosterone concentration. Creatine kinase activity was high at 60 weeks in treatments that were characterised by poor reproductive status and the activities of other enzymes reflected differences in reproductive status and mortality. 6. There was no long-term welfare or production advantage from feeding low protein rations or more generous feeding during the rearing period compared with conventional food restriction programmes.

Animal Husbandry↗

PubMed2002

Effects of low dietary protein and different allocations of food during rearing and restricted feeding after peak rate of lay on egg production, fertility and hatchability in female broiler breeders.

1. A 3x2x2 factorial experiment was conducted with boiler breeder females to determine the effects of body weight gain (three levels) and conventional or lower crude protein concentrations in the rations during rearing, and restricted or ad libitum feeding after the peak rate of lay on egg production, fertility, hatchability, mortality and food consumption. 2. Compared with ad libitum feeding, conventional food restriction resulted in a decrease in average daily food consumption of 0.6 during rearing, 0.2 during early lay and an increase of 0.4 after the peak rate of egg production. Mortality was decreased by more than half. 3. Restricted birds had higher total and settable egg production, fewer defective or damaged eggshells and higher fertility and hatchability than those fed ad libitum. The modified (more generous) rearing programme resulted in lower rates of egg production and higher rates of mortality compared with the conventional food restriction programme. 4. Low-protein rearing rations were associated with higher rates of food intake, higher mortalities and lower rates of egg production than the conventional protein rations. There were no differences in the fertility or hatchability of eggs between birds fed on the two concentrations of dietary crude protein. 5. Ad libitum feeding post-peak was associated with higher rates of mortality to 60 weeks of age. Post-peak feeding had little effect on the rate of lay or egg weight in conventionally restricted birds fed high protein rations or in birds fed ad libitum. Restricted feeding post-peak decreased the rate of lay and egg weight in birds on the modified restriction programme and in conventionally restricted birds fed on the low protein rations. There was no effect of post-peak feeding on fertility or hatchability of eggs. 6. The total numbers of saleable chicks per kg food consumed were 1.83, 1.72 and 0.52 for conventional, modified and ad libitum feeding during rearing; 1.56 and 1.15 for restricted and ad libitum feeding post-peak: there were no differences associated with protein concentrations of rations fed during rearing.

Animal Welfare↗

PubMed2002

Effects of dietary calcium and phosphorus on mineral retention, growth, feed efficiency and walking ability in growing turkeys.

1. Large White male turkeys from a heavy commercial male-line were fed on 16 diets containing 4 concentrations of calcium (6, 10, 14 and 18 g/kg) and available phosphorus (3, 5, 7, 9 g/kg) in a 4 x 4 factorial experiment with three replicates (pens). Turkeys were weighed and food intakes recorded from 4 to 7, 8 to 10 and 11 to 13 weeks of age. 2. The diets containing 6 g/kg calcium and 5, 7 or 9 g/kg available phosphorus concentrations were associated with lower body weighs at 10 and 13 weeks of age. 3. Fewer than 6% of the turkeys had an abnormal gait at 13 weeks of age. 4. The optimum dietary concentrations were 10 g/kg of calcium and 3 g/kg of available phosphorus. It was concluded that these concentrations should be fed at least to 13 weeks of age. 5. Retentions of dietary calcium and phosphorus averaged 300 g/kg of intake. 6. Utilisation of dietary phytate ranged from 5 to 11 g/kg and it is recommended that organic phosphorus should be ignored in the formulation of diets for growing turkeys unless they are supplemented with a phytase enzyme.

6-Phytase↗

PubMed2002

Comparative changes in plasma concentrations of progesterone, oestradiol and LH during the ovulatory cycle in a multiple ovulating male line and a single ovulating traditional line of turkeys.

The aim of this study was to compare the profile of circulating concentrations of LH, progesterone and oestradiol in a multiple ovulating male line with that of a single ovulating line of traditional turkeys. Plasma samples from seven traditional and 12 male-line turkeys were obtained every 3 h for 36 h. Male-line and traditional turkeys had single peaks of LH and progesterone that were of similar duration in both lines. The mean height of the plasma peaks of LH and progesterone were similar in the two lines and there was no detectable peak plasma oestrogen concentration. Mean plasma concentrations of LH and oestrogen were higher in single compared with multiple ovulating turkeys, whereas there were no differences in mean plasma progesterone concentrations. The results indicate that the multiple ovulation state in genetically selected high-growth lines of turkey may be the result of a correlated response in the steroidogenic capacity of ovarian tissue associated with low plasma concentrations of oestrogen rather than of a disturbance in the hormone profile of the ovulatory cycle.

Animals↗

PubMed2001

Effects of anti-inflammatory steroid drugs on pain coping behaviours in a model of articular pain in the domestic fowl.

The optimum dose rates of betamethasone, dexamethasone (sodium phosphate) and methylprednisolone (acetate salt) were determined for the treatment of inflammatory pain in domestic fowl using the microcrystalline sodium urate model of articular pain. The response criteria were the changes in behavioural profiles and pain-related activity over 60 minutes commencing 1 hour after an intra-articular injection of sodium urate and a course of intramuscular injections of a range of doses of each drug on the previous 2 days. The optimum dose rates for betamethasone, dexamethasone and methylprednisolone respectively were 0.04, 0.06 and 2 mg kg(-1)and are in the range of the recommended doses for these drugs in mammals.

Animals↗

PubMed2001

Effects of ambient temperature and restricted feeding on the growth of feathers in growing turkeys.

1. Male turkeys were reared to 6 weeks of age at 15 degrees C and 26 degrees C and fed ad libitum or restricted to 0.5 of the body weight of birds fed ad libitum. Basal metabolic rate was determined by indirect calorimetry at an ambient temperature of 20 degrees C. 2. Turkeys at 15 degrees C were lighter than those kept at 26 degrees C. Feather lengths and weight were similar in both groups. Fasting heat production corrected for both metabolic body size and activity was greater in turkeys reared at 15 degrees C than those at 26 degrees C. 3. Cranial breast feathers were significantly longer in restricted birds than in those fed ad libitum in contrast to a proportional decrease in the lengths of other feathers of 0.1 to 0.3. Feather weight as a proportion of body weight was 0.072 in restricted turkeys compared with 0.046 in birds fed ad libitum. There was no difference in basal metabolic rate between ad libitum and restricted turkeys. 4. It was concluded that feather growth was maintained in preference to body and muscle growth and that rearing birds at 15 degrees C did not improve breast feather cover. It is suggested that the growth of breast feathers in turkeys fed ad libitum is impaired.

Animals↗

PubMed2001

Welfare assessment of modified rearing programmes for broiler breeders.

1. Female broiler breeders were fed ad libitum or a restricted quantity of food to achieve either a recommended body weight curve or a modified (linear) growth curve that allowed more generous feeding between 6 and 15 weeks of age. The birds were fed a ration containing either a normal or low concentration of crude protein. The welfare of the birds was assessed using a profile of indices of welfare at 6, 12, 18 and 24 weeks of age. 2. The low-protein ration decreased the body weight of birds fed ad libitum and restricted birds were fed substantially more of the low-protein ration to meet target body weights from 3 to 14 weeks of age. 3. The modified restricted rearing programme did not have an effect on indices of welfare. 4. Water intakes and plasma corticosterone concentrations were lower in restricted birds fed the low-protein ration and they spent more time resting, and less time spot-pecking, than birds fed the high-protein ration. 5. Birds fed ad libitum on both rations spent more time resting and less time foraging, drinking and spot-pecking than food restricted birds and were more fearful than restricted birds at 6, 12 and 18 weeks of age. 6. The heterophil:lymphocyte ratio in restricted birds was higher at 6 weeks and lower at 24 weeks compared with birds fed ad libitum. Humoral immunity was lower at 6 weeks of age in birds fed ad libitum and was similar at other ages. Cell-mediated immunity was similar among all treatments. 7. Plasma corticosterone concentrations were higher in restricted birds compared with birds fed ad libitum. Plasma creatine kinase activity was higher in birds fed ad libitum at 6, 12 and 18 weeks of age. Alkaline phosphatase and lactate dehydrogenase activity were higher whereas AST was lower in restricted birds compared with those fed ad libitum. 8. There was no evidence to support the use of low protein rations or linear growth curves to improve welfare in restricted broiler breeder females.

Aging↗

PubMed2001

Ovarian steroid hormone production in a multiple ovulating male line and a single ovulating traditional line of turkeys.

Ovarian production of oestradiol and progesterone was investigated in a single ovulating traditional line and a multiple ovulating male line of turkeys. The oestradiol output from small follicles in response to LH stimulation and the aromatase activity of the residual ovary were also compared. The multiple hierarchy of follicles in the male line was shown to consist of a series of follicles of a similar size and stage of physiological maturation. The follicles of the traditional line produced significantly greater quantities of oestradiol than those of the male line. Impaired oestradiol production may have resulted in the lower plasma oestradiol concentration observed in the male line. There was no difference in follicular progesterone output between the traditional-line and male-line turkeys. The oestradiol output of whole small white follicles in response to LH stimulation was similar in the two lines and the depressed steroidogenesis of the male line was not changed. The aromatase activity of the small follicles was also lower in the male line, and there was no evidence that the male line ovary produced oestradiol in quantities proportional to its size. The results demonstrated that the hierarchy of follicles in the male line consisted of groups of follicles of similar mass and hormone output and indicated that selection for increased meat yield may have resulted in reduced ovarian steroidogenesis in male-line turkeys, in comparison with traditional, unselected turkeys.

Animals↗

PubMed2000

Photo-induced synthesis of tomatidenol-based glycoalkaloids in Solanum phureja tubers.

The effect of light exposure on the steroidal glycoalkaloid content of Solanum phureja tubers has been investigated and compared with that in domesticated potato (Solanum tuberosum) tubers. The results indicated that the increase in the concentration of solanidine-based glycoalkaloids, alpha-solanine and alpha-chaconine was broadly similar in both species. However, in the S. phureja tubers, light exposure also induced the synthesis of tomatidenol-based glycoalkaloids. These have been identified as alpha- and beta-solamarine. These glycoalkaloids were not detected in tubers continually stored in darkness.

Alkaloids↗

PubMed2000

A comparison of the composition of epicuticular wax from red raspberry (Rubus idaeus L.) and hawthorn (Crataegus monogyna Jacq.) flowers.

Epicuticular waxes have been characterised from the flowers of raspberry and hawthorn, on both of which adult raspberry beetles (Byturus tomentosus) can feed. The flower wax from both species had similar alkane profiles and also contained long-chain alcohols, aldehydes and fatty acids. The range of the carbon numbers detected for these classes of compounds was broadly similar in both but the relative amounts of each differed between species. Raspberry flower wax also contained fatty acid methyl esters, a group of compounds that has rarely been detected in plant epicuticular waxes, however, these were not observed in hawthorn flower wax. Long-chain alcohol-fatty acid esters with carbon numbers ranging from C36 to C48 were also detected in both plant species. However, an examination of their constituent acids indicated that in hawthorn the esters based on the C16 fatty acid predominated, whilst in raspberry flower wax, esters based on the C20 fatty acid were most abundant. Both species also contained pentacyclic triterpenoids, which accounted for, on average, over 16 and 48% of the total wax extracted from raspberry and hawthorn flowers respectively. In the former, ursolic and oleanolic acids accounted for over 90% of the pentacyclic triterpenes, whilst hawthorn flower wax, in addition to containing these acids, also contained high relative concentrations of both free and esterified alpha- and beta-amyrins.

Alcohols↗

PubMed2000

Effects of food restriction or delayed photostimulation on ovarian follicle number, plasma oestradiol concentration and vaginal collagen content in male-line turkeys.

1. An experiment was conducted to test the hypothesis that severe food restriction throughout the onset of lay or delaying photostimulation by 5 weeks would decrease the number of ovarian hierarchical follicles in male-line turkeys. It was proposed that a decrease in the number of hierarchical follicles would lower plasma oestradiol concentration and be associated with higher vaginal collagen content and a lower propensity to prolapse of the oviduct. 2. Five weeks after photostimulation, neither restriction to 63% of ad libitum body weight nor delayed onset of photostimulation had any significant effect on follicle number, plasma oestradiol concentration or vaginal collagen content. 3. It was concluded that neither food restriction nor delayed photostimulation can be used to control the over-development of the ovarian hierarchy in male-line turkeys.

Animals↗

PubMed2000

Ovarian follicular dynamics in selected and control (relaxed selection) male- and female-lines of broiler breeders fed ad libitum or on restricted allocations of food.

1. The reproductive structures of 4 broiler breeder lines fed ad libitum or restricted were compared at 1st egg. The lines were contemporary male- and female-lines and their respective progenitor lines maintained without selection for 20 years. 2. The selected lines were larger and had more hierarchical yellow follicles than the relaxed lines. The numbers of positions in the hierarchy were greater in the selected lines. The number of atretic follicles and the proportion of multiple follicles were relatively high in the selected male-line. 3. There were more white follicles in the range 1.8 to 5.0 mm diameter in the selected male-line than in the relaxed line, whereas selection did not change white follicle numbers in the female-line. 4. Food restriction decreased the numbers of normal and atretic yellow follicles and the proportion of multiples but had no effect on the number of positions in the hierarchy. Restricted feeding decreased the number of white follicles 1.4 to 2.4 mm and increased follicles 2.4 to 5.0 mm diameter. 5. There was little change in age at 1st egg among lines fed ad libitum. Restricted feeding increased age at 1st egg and the difference was greater in female- than in male-lines and in relaxed compared with selected birds. 6. Abdominal fatness was similar among the lines fed ad libitum and was decreased by restricted feeding. 7. Oviduct weights were greater in selected than in relaxed lines and were decreased by restricted feeding only in the selected male-line. 8. The weight of the largest follicle was higher in the selected lines and in restricted compared with ad libitum-fed birds. Plasma triglyceride concentrations were lower in restricted birds from the selected and relaxed female-lines compared with the other groups. Differences in plasma oestrogen concentrations could not be detected.

Adipose Tissue↗

PubMed2000

Development of the reproductive system in turkeys with a high or low susceptibility to prolapse of the oviduct.

Lines of turkeys selected for rapid growth and high meat yield have an increased incidence of prolapse of the oviduct compared with unselected or traditional strains of turkeys. The development of the reproductive system and changes in plasma estrogen concentrations were compared in sire line and traditional turkeys with the aim of identifying any morphological or hormonal differences that could be associated with the high incidence of prolapse in the male line. Four turkeys from each strain were killed weekly from 0 to 7 wk postphotostimulation, and samples from prolapsed birds were obtained from field cases. There were no differences in the rate of development of the ovary, oviduct, uterus, vagina, sphincter ani muscle, or muscular cord of the ventral ligament between the two strains that could predispose the sire line to prolapse. Histological investigation of the uterus, vagina, muscular cord of the ventral ligament, and sphincter ani muscle 5 wk postphotostimulation in traditional, sire line, and prolapsed sire line turkeys did not reveal any differences that could be associated with prolapse. No prelay peak in plasma estradiol concentration was observed in either strain, and there was no evidence to suggest that plasma estradiol was higher in the sire line compared with the traditional turkeys. It was concluded that prolapse of the oviduct in sire line turkeys was not associated with any anatomical abnormalities or high plasma estradiol during reproductive development.

Anal Canal↗

PubMed1999

The relationships between vaginal collagen, plasma oestradiol and uterine prolapse in turkeys.

Uterine and vaginal collagen content and plasma oestradiol concentration were measured in traditional, male-line and prolapsed male-line turkeys to investigate the higher incidence of uterine prolapse in the male-line strain. The effect of exogenous oestradiol on vaginal collagen and plasma oestradiol was also tested in the traditional and male-line strains. Vaginal collagen was significantly lower in the male-line compared to the traditional-line, while it was lowest in prolapsed male-line turkeys. Plasma oestradiol concentration was higher in the traditional-line than the male-line. No difference in plasma oestradiol concentration was found between prolapsed and non-prolapsed male-line turkeys. Administration of oestradiol for 7 days significantly raised plasma oestradiol concentration but had no effect on vaginal collagen. Decreased vaginal collagen content was associated with uterine prolapse and may predispose the male-line strain to uterine prolapse. There was no evidence from these results to support an involvement of oestradiol in uterine prolapse in male-line turkeys.

Animals↗