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G. Fordyce

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Jayjit Majumdar

University of Kalyani

Prof. Nagwa Mohamed A . Aref

Ain Shams University

Christos Kanellopoulos

Université de Genève

University of Tartu

Viacheslav Kuleshov

Stockholm University

Suresh G S Giriyapur

Sugarcane Breeding Institute (Indian Council of Agricultural Research)

Hajee Mohammad Danesh Science & Technolgy University, Bangladesh

Orientador Externo- Mario Bernardo Filho

UERJ - Universidade do Estado do Rio de Janeiro / Rio de Janeiro State University

Angelos Kanellis

Aristotle University of Thessaloniki

Johannes W Dietrich

Ruhr University, Bochum

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Papers by G. Fordyce

Genetic parameters of female reproductive traits measured by ultrasound in beef cattle

Reproductive status of 4649 heifers and 2051 lactating cows was recorded in 7 herds representing ... more Reproductive status of 4649 heifers and 2051 lactating cows was recorded in 7 herds representing Brahman, Droughtmaster and Santa Gertrudis beef cattle breeds. The traits measured were incidence of ovarian corpus luteum (CL) discerned by realtime ultrasound inspection of the reproductive tract at approximately 600d of age in heifers, and stage of pregnancy in firstcalf lactating cows. At 600d the heifers averaged 340kg and 40% had detectable CL; lactating cows averaged 474kg and a 64% pregnancy rate. Estimates of heritability of incidence of CL at 600d (0.20 to 0.32) and stage of pregnancy in lactating cows (0.10 to 0.17) in the herds suggested that a substantial proportion of the trait variation was due to additive gene action. Small to moderate genetic correlation with other important traits and the range in trait EBVs suggested ample opportunity for genetic improvement of the traits by selection of superior breeding animals. Introduction Detectio

Bull selection and management for natural mating of beef herds

Male abnormalities in the tropics

Animal Production in Australia THE MEASUREMENT OF TEMPERAMENT IN CATTLE AND THE EFFECT OF EXPERIENCE AND GENOTYPE

The temperaments of oneand two-year-old bulls and heifers of six genotypes were individually asse... more The temperaments of oneand two-year-old bulls and heifers of six genotypes were individually assessed in five different situations by recording aspects of their behaviour. All of the scores were significantly positively correlated with each other. In general, Brahman cross cattle had higher scores (i.e. reacted more violently) than Africander cross cattle which in turn had higher scores than British breeds. Nematode infestation generally depressed the temperament scores. However the differences between genotypes and the effect of nematode infestation depended on the test situation chosen. Heritabilities were calculated for the score from three of the tests.

Reproductive performance of northern Australia beef herds. 8. Impact of rainfall and wild dog control on percentage fetal and calf loss

Animal Production Science, 2020

Context Dingoes and hybrid domestic dogs (wild dogs) are lethally managed, principally by large-s... more Context Dingoes and hybrid domestic dogs (wild dogs) are lethally managed, principally by large-scale baiting programs, to protect Australia’s AU$11.4 billion beef cattle industry from predation. This strategy is promoted by pest management agencies as best practice. Aim To investigate the impact of baiting frequency and rainfall on percentage fetal and calf loss. Methods Using 64 property-years of data from 31 properties located across Queensland and the Northern Territory, 14 171 mating outcomes were investigated to assess whether annual rainfall, relative to 124-year mean annual rainfall, and the frequency that wild dogs were lethally controlled on each property, influenced predicted fetal and calf loss. Key results No effect of baiting frequency on fetal and calf loss in mature cows was observed. Predicted fetal and calf loss was significantly higher in dry and very wet years than in moderate-rainfall years (P < 0.001). Losses were observed to be higher in first-lactation cow...

282 Accuracy of multi-trait genomic predictions for age at puberty in Northern Australian beef heifers

Journal of Animal Science, 2018

Abstract - CSIRO PUBLISHING - Animal Production Science

Abstract - CSIRO PUBLISHING - Animal Production Science

Trial introduction of the Willis dropped ovary technique for spaying cattle in northern Australia

Australian Veterinary Journal, 2003

Objective To compare the Willis dropped ovary technique with traditional spaying methods in exten... more Objective To compare the Willis dropped ovary technique with traditional spaying methods in extensive beef cattle herds in northern Australia. Procedure Three field trials were conducted simultaneously at different sites in northern Australia in 1996–97. Brahman and Brahman‐Shorthorn cross heifers (n = 219, 2 years, 250 to 378 kg) and cows (n = 211, 3 to 16 years, 256 to 540 kg) were allocated by stratified randomisation to three treatments: spaying using the Willis dropped ovary technique (WDOT); spaying using traditional paralumbar and vaginal methods; and unspayed. Following these procedures, these nonpregnant, nonlactating cattle were then exposed to bulls (4 per 100 females) under extensive rangeland conditions for 12 months during which time weight, body condition, pregnancy and ovarian function were monitored and compared. Results Pregnancy rates varied from 60 to 90% for entire heifers and 80 to 100% for entire cows depending on site. The traditional spay methods were 100% s...

Contraceptive efficacy of an intra-uterine device in Brahman cattle

Animal Reproduction Science, 2001

The contraceptive efficacy of an intra-uterine device was evaluated using 218 heifers and 212 cow... more The contraceptive efficacy of an intra-uterine device was evaluated using 218 heifers and 212 cows on three north Australian cattle stations. The heifers were aged approximately 2 years and weighed 250-378 kg; the cows were aged 3-16 years and weighed 256-540 kg. All cattle were non-pregnant, non-lactating Brahmans. At the end of the monsoon (wet) season (April-June 1997), the cattle were allocated by stratified randomisation to the three treatments which were untreated controls (n = 59), surgical ovariectomy (n = 105), or implantation with a bovine intra-uterine device (BIUD; n = 266). All cattle grazed and were managed as one group within each station. They were exposed to bulls (4 per 100 females) from soon after treatment until slaughter approximately 12 months later. The BIUD could not be implanted in 25% of heifers and 8% of cows due to narrow or twisted cervices. Correct placement of the BIUDs appeared to be achieved in 57% of heifers and 72% of cows. At slaughter, the devices were incorrectly positioned in 73% of heifers and 49% of cows ଝ All studies were approved under the guidelines of the "Australian Code of Practice for the Care and Use of Animals for Scientific Purposes". Agriculture Western Australia Animal Experimentation Ethics Committee approved studies at Flora Valley Station: Approval 06-96-30. The Tropical Beef Centre Animal Experimentation Ethics Committee approved studies at Havilah and Canobie Stations: Ethical Clearance Certificate Number TBC87.

Effect of reproductive status, body condition and age of Bos indicus cross cows early in a drought on survival and subsequent reproductive performance

Australian Journal of Experimental Agriculture, 1990

A herd of 802 Brahman cross cows, managed under extensive conditions (7000 ha paddock with twice-... more A herd of 802 Brahman cross cows, managed under extensive conditions (7000 ha paddock with twice-yearly handling) in a dry tropical environment, was studied during the severe drought of 1982-83. Twenty-one per cent of the cows died. Cows more advanced in pregnancy and those in poorer condition in the early stages of the drought had lower (P<0.05) survival probabilities. Cows aged over 7 years also generally had a reduced (P<0.05) probability of survival. Calf loss between confirmed pregnancy early in the drought and weaning after the following wet season was 31%. Calf loss from surviving cows was not higher than is usual in non-drought years. All deaths of lactating cows were associated with calf deaths. The practical use of these results in cost-efficient management for survival of cows in drought was then evaluated in a second study in which 293 cows were drafted into high- and low-supplement-requirement (HSR and LSR) groups in the early stages of the 1987 drought. Survival ...

Prepartum supplementation effects on growth and fertility in Bos indicus-cross cows

Australian Journal of Experimental Agriculture, 1997

Summary. Three experiments were conducted in the dry tropics of north Australia using Bos indicus... more Summary. Three experiments were conducted in the dry tropics of north Australia using Bos indicus-cross cows. Cows in mid–late pregnancy were either unsupplemented during the late dry season or offered ad libitum (2 kg/day) molasses with 7.4% urea (w/w) (M8U) or cottonseed meal (1 kg/day) for up to 54 days commencing 2 months before the start of the calving season. Supplementation reduced weight loss in experiments 1 and 2 (P<0.05), but had no significant effect on weight or body condition in experiment 3. Supplementation had no effect on subsequent calf growth or cow lactation yields. Following early wet season rains in experiment 1, 9 and 49% of cows were ovulating 40 and 80 days post-partum, respectively, with no effect of supplementation. In experiment 2, 10 and 100% of cows had ovulated by 60 and 200 days post-partum, respectively. At any time between 80 and 180 days post-partum, supplemented cows were more likely to be cycling (P<0.05), independent of supplementation eff...

An evaluation of visual assessment for fertility in Brahman cross cows using the Bonsma technique

Theriogenology, 1995

A technique of visual assessment of cattle for reproductive efficiency, described by Professor Ja... more A technique of visual assessment of cattle for reproductive efficiency, described by Professor Jan Bonsma of South Africa, was evaluated in two well-managed large herds of % to X Brahman cross heifers and cows located in the dry tropics of north Australia. Individual lifetime performance records were available for all animals. Experienced cattlemen carried out the assessments. Higher scores were previously claimed to indicate higher fertility. The technique had high repeatability (0.7) and was quickly learned by the assessors. Scores from visual assessment had no useful predictive value for either heifer or cow fertility or for growth rate up to 27 mo of age, although 2.5yr-old heifers which were scored as subfertile matured into 4% smaller cows than heifers which had scored higher. Scores decreased as fatness increased (P<O.O5). Some biases in visual assessment occurred. Lactating cows scored higher than nonlactating cows (P<O.(w), independently of their reproductive record. Red and grey cows scored higher than brindle and black/brown cows (PcO.05). Bonsma scores were not influenced by the percentage of Brahman in the genotype. Significant, but apparently random, age effects on scores also occurred. It was concluded that the visual assessment criteria described by Bonsma were of no practical value in assessing potential productivity of breeding animals in well-managed Brahman cross cattle in the dry tropics.

Finding genes for economically important traits: Brahman cattle puberty

by Marina R. S. Fortes and G. Fordyce

Age at puberty is an important component of reproductive performance in beef cattle production sy... more Age at puberty is an important component of reproductive performance in beef cattle production systems. Brahman cattle are typically late-pubertal relative to Bos taurus cattle and so it is of economic relevance to select for early age at puberty. To assist selection and elucidate the genes underlying puberty, we performed a genome-wide association study (GWAS) using the BovineSNP50 chip (~54 000 polymorphisms) in Brahman bulls (n = 1105) and heifers (n = 843) and where the heifers were previously analysed in a different study. In a new attempt to generate unbiased estimates of single-nucleotide polymorphism (SNP) effects and proportion of variance explained by each SNP, the available data were halved on the basis of year and month of birth into a calibration and validation set. The traits that defined age at puberty were, in heifers, the age at which the first corpus luteum was detected (AGECL, h 2 = 0.56 AE 0.11) and in bulls, the age at a scrotal circumference of 26 cm (AGE26, h 2 = 0.78 AE 0.10). At puberty, heifers were on average older (751 AE 142 days) than bulls (555 AE 101 days), but AGECL and AGE26 were genetically correlated (r = 0.20 AE 0.10). There were 134 SNPs associated with AGECL and 146 SNPs associated with AGE26 (P < 0.0001). From these SNPs, 32 (~22%) were associated (P < 0.0001) with both traits. These top 32 SNPs were all located on Chromosome BTA 14, between 21.95 Mb and 28.4 Mb. These results suggest that the genes located in that region of BTA 14 play a role in pubertal development in Brahman cattle. There are many annotated genes underlying this region of BTA 14 and these are the subject of current research. Further, we identified a region on Chromosome X where markers were associated (P < 1.00E-8) with AGE26, but not with AGECL. Information about specific genes and markers add value to our understanding of puberty and potentially contribute to genomic selection. Therefore, identifying these genes contributing to genetic variation in AGECL and AGE26 can assist with the selection for early onset of puberty.

Hydration in non-suckling neonatal Brahman-cross calves

Australian Veterinary Journal, 2015

To identify measures that most closely relate to hydration in healthy Brahman-cross neonatal calv... more To identify measures that most closely relate to hydration in healthy Brahman-cross neonatal calves that experience milk deprivation. In a dry tropical environment, eight neonatal Brahman-cross calves were prevented from suckling for 2-3 days during which measurements were performed twice daily. Mean body water, as estimated by the mean urea space, was 74 ± 3% of body weight at full hydration. The mean decrease in hydration was 7.3 ± 1.1% per day. The rate of decrease was more than three-fold higher during the day than at night. At an ambient temperature of 39°C, the decrease in hydration averaged 1.1% hourly. Measures that were most useful in predicting the degree of hydration in both simple and multiple-regression prediction models were body weight, hindleg length, girth, ambient and oral temperatures, eyelid tenting, alertness score and plasma sodium. These parameters are different to those recommended for assessing calves with diarrhoea. Single-measure predictions had a standard error of at least 5%, which reduced to 3-4% if multiple measures were used. We conclude that simple assessment of non-suckling Brahman-cross neonatal calves can estimate the severity of dehydration, but the estimates are imprecise. Dehydration in healthy neonatal calves that do not have access to milk can exceed 20% (&amp;amp;gt;15% weight loss) in 1-3 days under tropical conditions and at this point some are unable to recover without clinical intervention.

Pregnancy effects on carcass and meat quality attributes of cows

Animal Production, 1990

ABSTRACT

Improved detection of bovine reproductive disease pathogens

Immunopathology of experimental Brucella abortus strain 19 infection of the genitalia of bulls

Veterinary Immunology and Immunopathology, 1990

Standardising bull breeding soundness evaluations and reporting in Australia

by Scott Norman and G. Fordyce

Theriogenology, 2006

There is substantial variation in bull breeding soundness evaluation procedures and reports in Au... more

Changing beef markets: should north Queensland producers change management to meet them?

... Saiwahl crosses do not offer production advantages over Brahman crosses (Holroyd et al. ... T... more

Genetic parameters of female reproductive traits measured by ultrasound in beef cattle

Reproductive status of 4649 heifers and 2051 lactating cows was recorded in 7 herds representing ... more Reproductive status of 4649 heifers and 2051 lactating cows was recorded in 7 herds representing Brahman, Droughtmaster and Santa Gertrudis beef cattle breeds. The traits measured were incidence of ovarian corpus luteum (CL) discerned by realtime ultrasound inspection of the reproductive tract at approximately 600d of age in heifers, and stage of pregnancy in firstcalf lactating cows. At 600d the heifers averaged 340kg and 40% had detectable CL; lactating cows averaged 474kg and a 64% pregnancy rate. Estimates of heritability of incidence of CL at 600d (0.20 to 0.32) and stage of pregnancy in lactating cows (0.10 to 0.17) in the herds suggested that a substantial proportion of the trait variation was due to additive gene action. Small to moderate genetic correlation with other important traits and the range in trait EBVs suggested ample opportunity for genetic improvement of the traits by selection of superior breeding animals. Introduction Detectio

Bull selection and management for natural mating of beef herds

Male abnormalities in the tropics

Animal Production in Australia THE MEASUREMENT OF TEMPERAMENT IN CATTLE AND THE EFFECT OF EXPERIENCE AND GENOTYPE

The temperaments of oneand two-year-old bulls and heifers of six genotypes were individually asse... more The temperaments of oneand two-year-old bulls and heifers of six genotypes were individually assessed in five different situations by recording aspects of their behaviour. All of the scores were significantly positively correlated with each other. In general, Brahman cross cattle had higher scores (i.e. reacted more violently) than Africander cross cattle which in turn had higher scores than British breeds. Nematode infestation generally depressed the temperament scores. However the differences between genotypes and the effect of nematode infestation depended on the test situation chosen. Heritabilities were calculated for the score from three of the tests.

Reproductive performance of northern Australia beef herds. 8. Impact of rainfall and wild dog control on percentage fetal and calf loss

Animal Production Science, 2020

Context Dingoes and hybrid domestic dogs (wild dogs) are lethally managed, principally by large-s... more Context Dingoes and hybrid domestic dogs (wild dogs) are lethally managed, principally by large-scale baiting programs, to protect Australia’s AU$11.4 billion beef cattle industry from predation. This strategy is promoted by pest management agencies as best practice. Aim To investigate the impact of baiting frequency and rainfall on percentage fetal and calf loss. Methods Using 64 property-years of data from 31 properties located across Queensland and the Northern Territory, 14 171 mating outcomes were investigated to assess whether annual rainfall, relative to 124-year mean annual rainfall, and the frequency that wild dogs were lethally controlled on each property, influenced predicted fetal and calf loss. Key results No effect of baiting frequency on fetal and calf loss in mature cows was observed. Predicted fetal and calf loss was significantly higher in dry and very wet years than in moderate-rainfall years (P < 0.001). Losses were observed to be higher in first-lactation cow...

282 Accuracy of multi-trait genomic predictions for age at puberty in Northern Australian beef heifers

Journal of Animal Science, 2018

Abstract - CSIRO PUBLISHING - Animal Production Science

Abstract - CSIRO PUBLISHING - Animal Production Science

Trial introduction of the Willis dropped ovary technique for spaying cattle in northern Australia

Australian Veterinary Journal, 2003

Objective To compare the Willis dropped ovary technique with traditional spaying methods in exten... more Objective To compare the Willis dropped ovary technique with traditional spaying methods in extensive beef cattle herds in northern Australia. Procedure Three field trials were conducted simultaneously at different sites in northern Australia in 1996–97. Brahman and Brahman‐Shorthorn cross heifers (n = 219, 2 years, 250 to 378 kg) and cows (n = 211, 3 to 16 years, 256 to 540 kg) were allocated by stratified randomisation to three treatments: spaying using the Willis dropped ovary technique (WDOT); spaying using traditional paralumbar and vaginal methods; and unspayed. Following these procedures, these nonpregnant, nonlactating cattle were then exposed to bulls (4 per 100 females) under extensive rangeland conditions for 12 months during which time weight, body condition, pregnancy and ovarian function were monitored and compared. Results Pregnancy rates varied from 60 to 90% for entire heifers and 80 to 100% for entire cows depending on site. The traditional spay methods were 100% s...

Contraceptive efficacy of an intra-uterine device in Brahman cattle

Animal Reproduction Science, 2001

The contraceptive efficacy of an intra-uterine device was evaluated using 218 heifers and 212 cow... more The contraceptive efficacy of an intra-uterine device was evaluated using 218 heifers and 212 cows on three north Australian cattle stations. The heifers were aged approximately 2 years and weighed 250-378 kg; the cows were aged 3-16 years and weighed 256-540 kg. All cattle were non-pregnant, non-lactating Brahmans. At the end of the monsoon (wet) season (April-June 1997), the cattle were allocated by stratified randomisation to the three treatments which were untreated controls (n = 59), surgical ovariectomy (n = 105), or implantation with a bovine intra-uterine device (BIUD; n = 266). All cattle grazed and were managed as one group within each station. They were exposed to bulls (4 per 100 females) from soon after treatment until slaughter approximately 12 months later. The BIUD could not be implanted in 25% of heifers and 8% of cows due to narrow or twisted cervices. Correct placement of the BIUDs appeared to be achieved in 57% of heifers and 72% of cows. At slaughter, the devices were incorrectly positioned in 73% of heifers and 49% of cows ଝ All studies were approved under the guidelines of the "Australian Code of Practice for the Care and Use of Animals for Scientific Purposes". Agriculture Western Australia Animal Experimentation Ethics Committee approved studies at Flora Valley Station: Approval 06-96-30. The Tropical Beef Centre Animal Experimentation Ethics Committee approved studies at Havilah and Canobie Stations: Ethical Clearance Certificate Number TBC87.

Effect of reproductive status, body condition and age of Bos indicus cross cows early in a drought on survival and subsequent reproductive performance

Australian Journal of Experimental Agriculture, 1990

A herd of 802 Brahman cross cows, managed under extensive conditions (7000 ha paddock with twice-... more A herd of 802 Brahman cross cows, managed under extensive conditions (7000 ha paddock with twice-yearly handling) in a dry tropical environment, was studied during the severe drought of 1982-83. Twenty-one per cent of the cows died. Cows more advanced in pregnancy and those in poorer condition in the early stages of the drought had lower (P<0.05) survival probabilities. Cows aged over 7 years also generally had a reduced (P<0.05) probability of survival. Calf loss between confirmed pregnancy early in the drought and weaning after the following wet season was 31%. Calf loss from surviving cows was not higher than is usual in non-drought years. All deaths of lactating cows were associated with calf deaths. The practical use of these results in cost-efficient management for survival of cows in drought was then evaluated in a second study in which 293 cows were drafted into high- and low-supplement-requirement (HSR and LSR) groups in the early stages of the 1987 drought. Survival ...

Prepartum supplementation effects on growth and fertility in Bos indicus-cross cows

Australian Journal of Experimental Agriculture, 1997

Summary. Three experiments were conducted in the dry tropics of north Australia using Bos indicus... more Summary. Three experiments were conducted in the dry tropics of north Australia using Bos indicus-cross cows. Cows in mid–late pregnancy were either unsupplemented during the late dry season or offered ad libitum (2 kg/day) molasses with 7.4% urea (w/w) (M8U) or cottonseed meal (1 kg/day) for up to 54 days commencing 2 months before the start of the calving season. Supplementation reduced weight loss in experiments 1 and 2 (P<0.05), but had no significant effect on weight or body condition in experiment 3. Supplementation had no effect on subsequent calf growth or cow lactation yields. Following early wet season rains in experiment 1, 9 and 49% of cows were ovulating 40 and 80 days post-partum, respectively, with no effect of supplementation. In experiment 2, 10 and 100% of cows had ovulated by 60 and 200 days post-partum, respectively. At any time between 80 and 180 days post-partum, supplemented cows were more likely to be cycling (P<0.05), independent of supplementation eff...

An evaluation of visual assessment for fertility in Brahman cross cows using the Bonsma technique

Theriogenology, 1995

A technique of visual assessment of cattle for reproductive efficiency, described by Professor Ja... more A technique of visual assessment of cattle for reproductive efficiency, described by Professor Jan Bonsma of South Africa, was evaluated in two well-managed large herds of % to X Brahman cross heifers and cows located in the dry tropics of north Australia. Individual lifetime performance records were available for all animals. Experienced cattlemen carried out the assessments. Higher scores were previously claimed to indicate higher fertility. The technique had high repeatability (0.7) and was quickly learned by the assessors. Scores from visual assessment had no useful predictive value for either heifer or cow fertility or for growth rate up to 27 mo of age, although 2.5yr-old heifers which were scored as subfertile matured into 4% smaller cows than heifers which had scored higher. Scores decreased as fatness increased (P<O.O5). Some biases in visual assessment occurred. Lactating cows scored higher than nonlactating cows (P<O.(w), independently of their reproductive record. Red and grey cows scored higher than brindle and black/brown cows (PcO.05). Bonsma scores were not influenced by the percentage of Brahman in the genotype. Significant, but apparently random, age effects on scores also occurred. It was concluded that the visual assessment criteria described by Bonsma were of no practical value in assessing potential productivity of breeding animals in well-managed Brahman cross cattle in the dry tropics.

Finding genes for economically important traits: Brahman cattle puberty

by Marina R. S. Fortes and G. Fordyce

Age at puberty is an important component of reproductive performance in beef cattle production sy... more Age at puberty is an important component of reproductive performance in beef cattle production systems. Brahman cattle are typically late-pubertal relative to Bos taurus cattle and so it is of economic relevance to select for early age at puberty. To assist selection and elucidate the genes underlying puberty, we performed a genome-wide association study (GWAS) using the BovineSNP50 chip (~54 000 polymorphisms) in Brahman bulls (n = 1105) and heifers (n = 843) and where the heifers were previously analysed in a different study. In a new attempt to generate unbiased estimates of single-nucleotide polymorphism (SNP) effects and proportion of variance explained by each SNP, the available data were halved on the basis of year and month of birth into a calibration and validation set. The traits that defined age at puberty were, in heifers, the age at which the first corpus luteum was detected (AGECL, h 2 = 0.56 AE 0.11) and in bulls, the age at a scrotal circumference of 26 cm (AGE26, h 2 = 0.78 AE 0.10). At puberty, heifers were on average older (751 AE 142 days) than bulls (555 AE 101 days), but AGECL and AGE26 were genetically correlated (r = 0.20 AE 0.10). There were 134 SNPs associated with AGECL and 146 SNPs associated with AGE26 (P < 0.0001). From these SNPs, 32 (~22%) were associated (P < 0.0001) with both traits. These top 32 SNPs were all located on Chromosome BTA 14, between 21.95 Mb and 28.4 Mb. These results suggest that the genes located in that region of BTA 14 play a role in pubertal development in Brahman cattle. There are many annotated genes underlying this region of BTA 14 and these are the subject of current research. Further, we identified a region on Chromosome X where markers were associated (P < 1.00E-8) with AGE26, but not with AGECL. Information about specific genes and markers add value to our understanding of puberty and potentially contribute to genomic selection. Therefore, identifying these genes contributing to genetic variation in AGECL and AGE26 can assist with the selection for early onset of puberty.

Hydration in non-suckling neonatal Brahman-cross calves

Australian Veterinary Journal, 2015

To identify measures that most closely relate to hydration in healthy Brahman-cross neonatal calv... more To identify measures that most closely relate to hydration in healthy Brahman-cross neonatal calves that experience milk deprivation. In a dry tropical environment, eight neonatal Brahman-cross calves were prevented from suckling for 2-3 days during which measurements were performed twice daily. Mean body water, as estimated by the mean urea space, was 74 ± 3% of body weight at full hydration. The mean decrease in hydration was 7.3 ± 1.1% per day. The rate of decrease was more than three-fold higher during the day than at night. At an ambient temperature of 39°C, the decrease in hydration averaged 1.1% hourly. Measures that were most useful in predicting the degree of hydration in both simple and multiple-regression prediction models were body weight, hindleg length, girth, ambient and oral temperatures, eyelid tenting, alertness score and plasma sodium. These parameters are different to those recommended for assessing calves with diarrhoea. Single-measure predictions had a standard error of at least 5%, which reduced to 3-4% if multiple measures were used. We conclude that simple assessment of non-suckling Brahman-cross neonatal calves can estimate the severity of dehydration, but the estimates are imprecise. Dehydration in healthy neonatal calves that do not have access to milk can exceed 20% (&amp;amp;gt;15% weight loss) in 1-3 days under tropical conditions and at this point some are unable to recover without clinical intervention.

Pregnancy effects on carcass and meat quality attributes of cows

Animal Production, 1990

ABSTRACT

Improved detection of bovine reproductive disease pathogens

Immunopathology of experimental Brucella abortus strain 19 infection of the genitalia of bulls

Veterinary Immunology and Immunopathology, 1990

Standardising bull breeding soundness evaluations and reporting in Australia

by Scott Norman and G. Fordyce

Theriogenology, 2006

There is substantial variation in bull breeding soundness evaluation procedures and reports in Au... more

Changing beef markets: should north Queensland producers change management to meet them?

... Saiwahl crosses do not offer production advantages over Brahman crosses (Holroyd et al. ... T... more