In yearling heifers, WDOT spaying resulted in lower morbidity and short-term mortality compared with flank spaying. Both methods compromised the health and welfare of some animals for up to 4 days and body weight gains were reduced during the 6 weeks post spaying.

The welfare outcomes for Bos indicus cattle (100 heifers and 50 cows) spayed by either the dropped ovary technique (DOT) or ovariectomy via flank laparotomy (FL) were compared with cattle subjected to physical restraint (PR), restraint by electroimmobilization in conjunction with PR (EIM), and PR and mock AI (MAI). Welfare assessment used measures of morbidity, mortality, BW change, and behavior and physiology indicative of pain and stress. One FL heifer died at d 5 from peritonitis. In the 8-h period postprocedures, plasma bound cortisol concentrations of FL, DOT, and EIM cows were not different and were greater (P<0.05) than PR and MAI. Similarly, FL and DOT heifers had greater (P<0.05) concentrations than PR and MAI, with EIM intermediate. Creatine kinase and aspartate aminotransferase concentrations were greater (P<0.05) in FL and EIM heifers compared with the other treatments, with a similar pattern seen in the cows. Haptoglobin concentrations were significantly (P<0.05) increased in the FL heifers compared with other treatments in the 8- to 24-h and 24- to 96-h periods postprocedures, and in cows were significantly (P<0.05) increased in the FL and DOT compared with PR in the 24- to 96-h period. Behavioral responses complemented the physiological responses; standing head down was shown by more (P<0.05) FL cows and heifers to 3 d postprocedures compared with other treatments, although there was no difference between FL and DOT heifers at the end of the day of procedures. At this same time, fewer (P<0.05) FL and DOT heifers and cows were observed feeding compared with other treatments, although in cows there was no difference between FL, DOT, and EIM. There were no significant differences (P>0.05) between treatments in BW changes. For both heifers and cows, FL and DOT spaying caused similar levels of acute pain, but FL had longer-lasting adverse impacts on welfare. Electroimmobilization during FL contributed to the pain and stress of the procedure. We conclude that: i) FL and DOT spaying should not be conducted without measures to manage the associated pain and stress; ii) DOT spaying is preferable to FL spaying; iii) spaying heifers is preferable to spaying cows; and iv) electroimmobilization causes pain and stress and should not be routinely used as a method of restraint.

BackgroundCattle are bred for, amongst other factors, specific traits, including parasite resistance and adaptation to climate. However, the influence and inheritance of mitochondrial DNA (mtDNA) are not usually considered in breeding programmes. In this study, we analysed the mtDNA profiles of cattle from Victoria (VIC), southern Australia, which is a temperate climate, and the Northern Territory (NT), the northern part of Australia, which has a tropical climate, to determine if the mtDNA profiles of these cattle are indicative of breed and phenotype, and whether these profiles are appropriate for their environments.ResultsA phylogenetic tree of the full mtDNA sequences of different breeds of cattle, which were obtained from the NCBI database, showed that the mtDNA profiles of cattle do not always reflect their phenotype as some cattle with Bos taurus phenotypes had Bos indicus mtDNA, whilst some cattle with Bos indicus phenotypes had Bos taurus mtDNA. Using D-loop sequencing, we were able to contrast the phenotypes and mtDNA profiles from different species of cattle from the 2 distinct cattle breeding regions of Australia. We found that 67 of the 121 cattle with Bos indicus phenotypes from NT (55.4%) had Bos taurus mtDNA. In VIC, 92 of the 225 cattle with Bos taurus phenotypes (40.9%) possessed Bos indicus mtDNA. When focusing on oocytes from cattle with the Bos taurus phenotype in VIC, their respective oocytes with Bos indicus mtDNA had significantly lower levels of mtDNA copy number compared with oocytes possessing Bos taurus mtDNA (P < 0.01). However, embryos derived from oocytes with Bos indicus mtDNA had the same ability to develop to the blastocyst stage and the levels of mtDNA copy number in their blastocysts were similar to blastocysts derived from oocytes harbouring Bos taurus mtDNA. Nevertheless, oocytes originating from the Bos indicus phenotype exhibited lower developmental potential due to low mtDNA copy number when compared with oocytes from cattle with a Bos taurus phenotype.ConclusionsThe phenotype of cattle is not always related to their mtDNA profiles. MtDNA profiles should be considered for breeding programmes as they also influence phenotypic traits and reproductive capacity in terms of oocyte quality.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-017-0523-5) contains supplementary material, which is available to authorized users.

Context High and variable fetal and calf loss in beef herds occurs across northern Australia. Reasons for the majority of these losses, a major cost to the industry, have remained unknown. Aims The research question was, which of the 58 region-, property-, management group-, and animal-level risk factors measured are associated with pregnant females failing to wean their calf? Methods An epidemiological study measured fetal and calf loss (consistently expressed as % points) between confirmed pregnancy and weaning and the major associated risk factors using a selected population from 55 commercial beef breeding herds representing 23 166 pregnancies in the mostly dry tropical environment of northern Australia. Key results Median fetal and calf loss was 9.5% with large variation. Achievable levels appeared to be <10% for Northern Forest herds, and <5% for Southern Forest, Central Forest and Northern Downs herds. The risk factors most strongly associated with fetal and calf loss were low-fertility country type interacting with phosphorus inadequacy (up to 10% increase), low body condition score interacting with phosphorus inadequacy (up to 8% increase), tall cows (up to 4% increase), and high temperature–humidity index around calving interacting with country type (up to 7% increase). These are nutritional and environmental risk factors and had the combined highest individual effect and frequency. Other risk factors associated with fetal and calf loss included first-lactation cows, which interacted with mustering around calving (up to 9% increase), having not reared a calf in the previous year interacting with cow age (up to 8% increase), low mustering efficiency (up to 9% increase), perceived predation by wild dogs (4–5% increase), high prevalence of Campylobacter fetus sp. venerealis antibodies (7% increase), recent infection with bovine viral diarrhoea virus (9% increase), and inadequate dry-season protein (4% increase). Conclusions The combined effects of environmental, nutritional and management risk factors on fetal and calf loss in northern Australia were large and additive and were much greater, collectively up to 30–40%, and more consistent than that due to either endemic infectious diseases or animal factors. Implications Opportunity for remedial action is high and, for the effect of non-infectious risk factors, should target milk delivery to neonatal calves.

Context Sound reproductive efficiency is a key determinant for the overall productivity and profitability of a beef breeding business. Failure of a cow to conceive results in either culling or the cost of carrying non-pregnant animals. Aims This study aimed to determine and quantify the major factors associated with non-pregnancy in commercial beef breeding herds of northern Australia. Methods A prospective population-based epidemiological study of the likelihood of non-pregnancy in cows after an annual mating in northern Australian beef breeding cows used data from 73 herds from four broad country types and 62 323 animal years; approximately 80 property-, management-group- and cow-level risk factors were considered. A multivariable model building process was employed to scrutinise the resulting dataset, so as to identify what herd management practices, nutritional, environmental, and individual cow factors were associated with non-pregnancy and estimate their magnitude of effect. Key results Non-pregnancy was disproportionately high in the Northern Forest (32.1%), compared with the Northern Downs, Central Forest and Southern Forest where it was 17.1%, 16.0% and 13.2% respectively. Time of expected calving had the largest impact on occurrence of non-pregnancy. Parity also had a significant influence, with first-lactation cows typically having 5–12% higher non-pregnancy than did mature cows. Non-pregnancy decreased with an increasing body condition score at the branding/weaning muster for lactating cows. The difference in non-pregnancy when comparing availability of wet-season pasture phosphorus content and digestibility of pasture during the dry season was 13.2 and 10.2 percentage points respectively. Conclusions This study demonstrated the substantial impact environment, herd management practices, nutrition and disease factors can have on the reproductive performance of females. Implications To optimise the efficiency of females (through reducing the occurrence of non-pregnancy) under commercial conditions in northern Australia, production systems should support beef herds calving early in the production year, being in at least moderate body condition and having access to more digestible pastures that address the nutritional requirements for both protein and phosphorus. This indicates focus for management, especially in the Northern Forest where the likelihood of non-pregnancy was highest.

Hip height, body condition, subcutaneous fat, eye muscle area, percentage Bos taurus, fetal age and diet digestibility data were collected at 17 372 assessments on 2181 Brahman and tropical composite (average 28% Brahman) female cattle aged between 0.5 and 7.5 years of age at five sites across Queensland. The study validated the subtraction of previously published estimates of gravid uterine weight to correct liveweight to the non-pregnant status. Hip height and liveweight were linearly related (Brahman: P < 0.001, R2 = 58%; tropical composite P < 0.001, R2 = 67%). Liveweight varied by 12–14% per body condition score (5-point scale) as cows differed from moderate condition (P < 0.01). Parallel effects were also found due to subcutaneous rump fat depth and eye muscle area, which were highly correlated with each other and body condition score (r = 0.7–0.8). Liveweight differed from average by 1.65–1.66% per mm of rump fat depth and 0.71–0.76% per cm2 of eye muscle area (P < 0.01). Estimated dry matter digestibility of pasture consumed had no consistent effect in predicting liveweight and was therefore excluded from final models. A method developed to estimate full liveweight of post-weaning age female beef cattle from the other measures taken predicted liveweight to within 10 and 23% of that recorded for 65 and 95% of cases, respectively. For a 95% chance of predicted group average liveweight (body condition score used) being within 5, 4, 3, 2 and 1% of actual group average liveweight required 23, 36, 62, 137 and 521 females, respectively, if precision and accuracy of measurements matches that used in the research. Non-pregnant Bos taurus female cattle were calculated to be 10–40% heavier than Brahmans at the same hip height and body condition, indicating a substantial conformational difference. The liveweight prediction method was applied to a validation population of 83 unrelated groups of cattle weighed in extensive commercial situations on 119 days over 18 months (20 917 assessments). Liveweight prediction in the validation population exceeded average recorded liveweight for weigh groups by an average of 19 kg (~6%) demonstrating the difficulty of achieving accurate and precise animal measurements under extensive commercial grazing conditions.

A population-based epidemiological study was conducted between 2007 and 2011 and involved 78 northern Australian commercial beef-breeding herds and in excess of 56 000 cattle concurrently monitored. Cow reproductive performance was described from the biannual assessment of fetal age and lactation status. Both novel and well established measures of performance were used within four broad country types and included the following: percentage of lactating cows pregnant within 4 months of calving; percentage of cows pregnant within an approximate 12-month reproductive cycle (annual pregnancy); fetal and calf loss between confirmed pregnancy and weaning; percentage of cows contributing a calf at weaning and percentage of non-pregnant females retained for re-mating. The results from the present study described the variation in reproductive performance of commercial beef herds across northern Australia and defined typical and achievable levels of performance. The results from the study suggest that a weaning rate of 66% is a more realistic target level of performance for the Northern Forest, while weaning rates of at least 75–80% are realistic for other country types. Female-cattle performance was much lower in the Northern Forest than in the other country types. In absolute terms, there were 15–20% fewer surviving mated cows contributing a calf at weaning in an annual production year and ~4% more missing pregnant cows, which was associated with the ~20% higher retention of non-pregnant cows for re-mating. The reproductive performance of herds varied substantially among and within country types, with a 20–30% variation in reproduction rates and 5–15% variation in fetal and calf loss for half of the herds in all regions. Further analyses were performed and identified the major causes of this variation and are reported in subsequent papers within this series. The results from the present study appear to suggest that substantial opportunities to increase the reproductive performance of northern beef herds exist, providing that the causes of this variation are able to be identified and alleviated.

Bound cortisol responses in spayed heifers were elevated to 6 h post-procedure and similar in WDOT- and flank-spayed animals, indicating comparable levels of pain and stress. An inflammatory response, indicated by haptoglobin concentrations, was sustained for longer in Flank than in WDOT spayed heifers, suggesting longer-lasting adverse effects on welfare from flank spaying than WDOT spaying.