Assessing Extensive Cow-Calf Welfare in Namibia: Feasibility of Adapting a New Zealand Beef Cow Welfare Assessment Protocol.

Namibia needs a robust welfare assessment protocol for beef cattle for benchmarking and trade. As there is presently no such protocol, one was developed for Namibian conditions based on one designed for extensive beef cattle in New Zealand which had been derived from the Welfare Quality and UC Davis Cow-Calf protocols, the modified protocol was evaluated in a semi-commercial farming village during the pregnancy testing of 141 cows from 5 herds of different households. Animal- and stockperson-based measures were assessed directly, cows were observed at grazing, and a questionnaire-guided interview was conducted. The protocol provided a good basis for welfare assessment, but additional measures and modifications were needed for the Namibian system. These were the effects of recurrent drought, predation, plant poisoning, external parasites, walking long distances to water and grazing, compulsory hot-iron branding, extraneous cattle marking, and variable standards of handling facilities. The protocol was modified to incorporate these changes, resulting in a total of 40 measures. It now needs full validation through widespread testing across the range of beef production systems used in Namibia.

Widening access to veterinary education: descriptive analysis of ethnicity, societal representation and educational background of applicants to veterinary education in Aotearoa New Zealand.

AIMS: To describe the ethnicity of domestic applicants for selection into the professional phase of veterinary education in Aotearoa New Zealand from 2003 to 2019, and to compare this with the ethnic composition of New Zealand society. This study also aims to explore whether there are differences in the demographic features and educational background of Maori applicants compared to non-Maori applicants that may be relevant to widening access to veterinary education. METHODS: This study was conducted with a Kaupapa Maori research methodology. Data for all applicants to the Bachelor of Veterinary Science programme at Massey University (Palmerston North, NZ) from 2003 to 2019 were retrieved from the university's Student Management System and the School of Veterinary Science selection application databases. Self-identified ethnicity was analysed in four time periods (2003-2006, 2007-2012, 2013-2016, 2017-2019) defined by factors that might influence whether an individual chose to apply for selection into the veterinary programme. Gender, age, previous university experience, decile and type of high school, and being first in family to attend university were compared between Maori and non-Maori. RESULTS: From 2003 to 2019, 3,819 individuals submitted 4,802 applications for selection into the veterinary programme. Across all time periods, applicants who identified as Maori (274/4,802; 5.7%) or Pacific (56/4,802; 1.2%) were underrepresented compared to the New Zealand population (Maori 16.5%; Pacific 8.1%), while applicants who identified as European (4,035/4,802; 84%) were over-represented (70.2% of the New Zealand population). The proportion of Maori (p = 0.82) and Pacific (p = 0.31) applicants did not change over time, while the proportion of European applicants decreased from 853/968 (88.1%) to 823/977 (84.2%; p < 0.001). Compared to non-Maori, Maori applicants were more likely to have attended a lower decile school (p < 0.001), have attended a state rather than private or overseas school (p = 0.003) and to have been the first in their family to attend university (p = 0.001). CONCLUSIONS: Maori are underrepresented in the veterinary applicant pool and veterinary profession in comparison to the New Zealand population. Additionally, Maori applicants differed from non-Maori applicants in pre-university factors that are barriers to university attendance. Implementing activities and processes aimed at widening veterinary programme access with the eventual goal of improving the ethnic representation of the veterinary workforce needs to be a priority for the university and profession.

Quantitative and thematic analysis of complaints by clients against clinical veterinary practitioners in New Zealand.

AIMS: To provide a descriptive analysis of all notifications and complaints received by the Veterinary Council of New Zealand (VCNZ) during 1992-2016 and to use a thematic analysis of complaints made by clients to the VCNZ during 2013-2015 to determine the underlying reasons for their complaints. METHODS: A mixed methods approach was used. Notifications and complaints against veterinarians between 1992-2016 (n=1218) were summarised based on complaint categories and by gender of the veterinarian respondents, the number of years registered with the VCNZ and the animal species to which the complaint related. In-depth thematic analysis was made of the content of clients' complaints between 2013-2015 (n=141) to identify details of the key themes and subthemes underlying the complaints. RESULTS: The VCNZ categorised 595/959 (62.0%) of the complaints made between 1992-2016 as related to technical competency, and 308/959 (32%) to professional behaviour. Of the 1,218 complaints, 818 (67.2%) were not investigated or were dismissed, and 18 (1.5%) cases were upheld due to technical competency concerns. Of the complaints in which animal species was identified, 623/738 (84.4%) involved companion animals and 104/738 (14.1%) involved large animals. Male veterinarians were the subject of 855/1,218 (70.2%) complaints. Of the complaints that recorded the number of years the respondent had been registered, 488/1,121 (43.5%) involved veterinarians who had been registered ≥21 years. Thematic analysis identified client expectations as the one overarching theme, within which were four subthemes; a veterinarian would be trustworthy and honest, provide good quality care, communicate in a way that the client finds acceptable, and charge fairly. CONCLUSIONS AND CLINICAL RELEVANCE: Notifications and complaints against male practitioners outnumbered those against female practitioners, and companion animal practitioners were over-represented. Many complaints that were ostensibly related to technical failures, were shown by thematic analysis to also represent underlying failures of professional behaviour. Key issues included lack of trustworthiness, honesty, good quality care and acceptable communication with the client. These data should not be interpreted as an accurate indicator of the prevalence of misconduct in practice, as the proportion of dissatisfied clients who did not raise a notification or complaint is unknown. Accurate classification of complaints will enable veterinary regulators and educators to identify competencies that could be developed or improved through training and experience.

Effects of GnRH, a progesterone-releasing device, and energy balance on an oestrus synchronisation program in anoestrous dairy cows.

OBJECTIVE: The aim of this research was to study the roles of the day 0 energy balance and gonadotrophin-releasing hormone (GnRH) and progesterone levels on dominant follicle (DF) and corpus luteum (CL) development during the first 7 days of a gonadotrophin-prostaglandin-gonadotrophin (GPG) + progesterone (P4) program in anoestrous dairy cows. METHODS: Cows (n = 81) were allocated to one of the three treatments: (1) GPG + P4 (days 0 and 9, 100 µg GnRH; day 0-7, intravaginal P4 device; day 7, 500 µg PGF2α ); (2) GPG (as for treatment 1 but excluding the P4 device) and (3) prostaglandin + GnRH + P4 (as for treatment 1, but excluding day 0 GnRH). DF and CL size, plasma concentrations of insulin, insulin-like growth factor-I (IGF-I) and non-esterified fatty acid (NEFA) were measured on days 0 and 7. RESULTS: The proportion of cows with a CL on day 7 was significantly different between groups (GPG: 78%, GPG+P4: 69%, PGF2α + GnRH + P4: 42%, P = 0.02). The CL volume on day 7 was significantly associated with treatment, treatment by time postpartum and plasma concentrations of insulin, IGF-I and NEFA. CONCLUSION: In cows without a CL present on day 0 of an oestrus synchronisation program, removal of the day 0 GnRH treatment led to reduced CL development; however, no effect of adding progesterone was found. In contrast, in cows with a CL present on day 0 inclusion of a progesterone device led to a higher CL volume, but removal of the first GnRH injection had no effect. Response to the treatment was affected by plasma concentrations of insulin, IGF-I and NEFA.

Effects of progesterone inclusion in a gonadotropin-prostaglandin-gonadotropin programme on follicular dynamics and ovulation synchronisation of pasture-based dairy cows with anoestrous.

The aim of this study was to evaluate how the addition of a progesterone device to a gonadotropin-prostaglandin-gonadotropin (GPG) programme in dairy cows with postpartum anovulatory anoestrus affected ovarian follicular dynamics and the synchronisation of ovulation. Twenty-two dairy cows were randomly assigned to either GPG (Day 0: 100 µg GnRH, Day 7: 500 µg PGF2α, Day 9: 100 µg GnRH, Day 0-7: Day 10) or GPG with a progesterone device from Day 0 to 7 (GPG+P4). Ovarian follicular dynamics and ovulation synchronisation were studied using transrectal ultrasonography. Compared to the GPG+P4, GPG alone resulted in a relatively larger mean dominant follicle size and a higher mean peripheral oestradiol concentration (74.9 pg ∗ day vs. 60.6 pg ∗ day; P=0.002); however, there was much greater variation in follicle diameter in the group treated with GPG (7.8-22 mm vs. 10.8-17.5mm in GPG+P4) and this may, at least partly explain why only 7/11 cows in this group ovulated within 48 h of the Day 9 GnRH injection compared to 10/10 of the cows in the GPG+P4 group. These results suggest that differences in follicular dynamics between GPG and GPG+P4 programmes are not a key driver of the difference in conception rate, but further studies are required to better assess the role of ovulation synchronisation.

Susceptibility to antimicrobials of mastitis-causing Staphylococcus aureus, Streptococcus uberis and Str. dysgalactiae from New Zealand and the USA as assessed by the disk diffusion test.

OBJECTIVE: To compare the antimicrobial susceptibility patterns of three common mastitis pathogens (Staphylococcus aureus, Streptococcus uberis and Str. dysgalactiae) isolated from milk samples from New Zealand and the USA. METHODS: A total of 182 S. aureus, 126 Str. uberis and 89 Str. dysgalactiae isolates from New Zealand (107, 106 and 41, respectively) and the USA (75, 20 and 48, respectively) were assessed using the disk diffusion test. RESULTS: Susceptibility varied among the bacterial species. All isolates were susceptible to the amoxicillin-clavulanic acid combination. Resistance to lincomycin was most frequent (susceptibility of 8.6%) across all species. Non-susceptible (i.e. resistant or intermediate) isolates of S. aureus were identified for the three non-isoxazolyl penicillins (amoxicillin, ampicillin and penicillin: 20.6% and 36.0%) and lincomycin (99.9% and 94.6%) for NZ and the USA, respectively. Resistance to erythromycin (5.3%) and tetracyclines (6.7%) was detected only in isolates from the USA. There were differences in susceptibility between Str. uberis and Str. dysgalactiae; all streptococcal isolates demonstrated resistance to aminoglycosides (neomycin 52.4% and streptomycin 27.9%) and enrofloxacin (28%). Resistance of Str. dysgalactiae to tetracycline was almost 100.0% and to oxytetracycline 89.9%. CONCLUSION AND CLINICAL RELEVANCE: Most of the isolates tested were susceptible to most of the antimicrobials commonly used for treatment of bovine mastitis, with the exception of the lincosamides. Susceptibility to a selected class-representative antimicrobial and at the genus level should be interpreted with caution. Differences between NZ and the USA confirm the value of national surveys to determine the susceptibility patterns of mastitis pathogens.

Conception rates to fixed-time artificial insemination of two oestrus synchronisation programmes in dairy heifers.

AIM: To evaluate the conception rate to fixed-time artificial insemination (FTAI) of two oestrus synchronisation programmes in dairy heifers on eight farms over 2 years. METHODS: The study was conducted in 2008 and 2010 on eight farms near Palmerston North, New Zealand. Nulliparous Friesian and Friesian×Jersey heifers (13-15 months of age) were randomly allocated to one of two oestrus synchronisation programmes. Group 1 (GPG+P4; n=330), received gonadotrophin-releasing hormone (GnRH) I/M on Day 0, a progesterone (P4)-releasing intravaginal device from Days 0-7, prostaglandin F2α (PGF) I/M on Day 7 and a second dose of GnRH at the time of FTAI on Day 9. The second group (P4+PGF; n=343) received a P4-releasing intravaginal device from Days 0-7, PGF on Day 6 and FTAI on Day 9. Pregnancy was diagnosed from Days 42-52 by transrectal ultrasonography. RESULTS: The overall conception rate was 52.4% and 54.8% for the GPG+P4 and P4+PGF groups, respectively. The odds of conception for the two treatments were not different (OR=0.90; 95% CI=0.67-1.23), nor was there any difference between groups in different years (p=0.58). Farm affected conception rate (p=0.002), but there was no interaction with treatment (p=0.92) . CONCLUSIONS: This study has shown that an alternative synchronisation programme can produce similar results in terms of conception rate to the GPG+P4 treatment, currently commonly used in heifers. More research is required to establish whether other modifications to the GPG+P4 programme can produce similar results at lower costs, and to identify and quantify farm factors which affect the economic benefit of heifer synchronisation. CLINICAL RELEVANCE: This study indicated that synchronising heifers with P4 and PGF resulted in conception rates equivalent to those resulting from a GPG+P4 treatment, but with reduced drug costs. However, because heifers in the GPG+P4 group received the second GnRH injection at the time of AI, they needed only three yardings as opposed to the four required for the heifers treated with P4 and PGF. Thus, the choice of programme for an individual farm will depend on that farm's circumstances, in particular the cost of yarding the heifers.

The effects of exclusion of progesterone or Day 0 GnRH from a GnRH, prostaglandin, GnRH + progesterone program on synchronization of ovulation in pasture-based dairy heifers.

This study evaluated the effect of removing the GnRH injection on Day 0 or the progesterone (P4) device from a GnRH, PGF2α, GnRH (GPG) + P4 program on follicular dynamics and synchronization of ovulation in dairy heifers. Friesian and Friesian × Jersey heifers, in autumn 2009 (n = 35) and spring 2010 (n = 38), were randomly allocated to one of three estrus synchronization programs. The first group (GPG + P4) received 100 µg GnRH on Day 0, a P4-releasing intravaginal device from Days 0 to 7, 500 µg PGF2α on Day 7, and 100 µg GnRH on Day 9, followed by fixed-time artificial insemination 16 to 20 hours later. The program for group 2 (GPG) was the same as group 1 with the exclusion of the P4 device. Group 3 (P + G + P4) was treated the same as group 1, except for the absence of the GnRH treatment on Day 0. Ultrasonography was performed on Days 0, 1, 2, 3, and 7 and then at 12 hourly intervals on Days 9 to 11. Dominant follicle size was affected by both treatment and day, and there was also a significant interaction (P < 0.02) between treatment and day. Mean dominant follicle size was larger in the heifers treated with P + G + P4 on Days 1 to 3 than those treated with GPG + P4 (P < 0.02) and, on Day 2, than those treated with GPG (P = 0.005). However, on Day 7, mean dominant follicle size was larger in heifers treated with GPG than heifers treated with P + G + P4 (P = 0.03). The emergence of a new follicular wave was later in heifers treated with P + G + P4 than heifers, which received a GnRH injection on Day 0 (4.3 ± 0.7 days, compared with combined GPG + P4 and GPG 3.0 ± 0.3 days; P = 0.03). The proportion of heifers that ovulated within the first 48 hours after the Day 9 injection of GnRH was not affected by treatment (GPG, 81%; GPG + P4, 84%; and P + G + P4, 100% [including early ovulation]; P = 0.11). The timing of the ovulation was not different between treatments (P = 0.97).

Association between placentome size, measured using transrectal ultrasonography, and gestational age in cattle.

AIM: The aim of this study was to estimate whether fetal age could be accurately estimated using placentome size. METHODS: Fifty-eight cows with confirmed conception dates in two herds were used for the study. The length of the long axis and cross-sectional area of placentomes close to the cervix were measured once every 10 days between approximately 60-130 days of gestation and once every 15 days between 130-160 days of gestation. Four to six placentomes were measured using transrectal ultrasonography in each uterine horn. A linear mixed model was used to establish the factors that were significantly associated with log mean placentome length and to create an equation to predict gestational age from mean placentome length. Limits of agreement analysis was then used to evaluate whether the predictions were sufficiently accurate for mean placentome length to be used, in practice, as a method of determining gestational age. RESULTS: Only age of gestation (p<0.001) and uterine horn (p=0.048) were found to have a significant effect on log mean placentome length. From the three models used to predict gestational age the one that used log mean placentome length of all placentomes, adjusting for the effect of horn, had the smallest 95% limits of agreement; ±33 days. That is, predicted gestational age had a 95% chance of being between 33 days greater and 33.7 days less than actual age. This is approximately twice that reported in studies using measurement of fetal size. CONCLUSIONS: Measurement of placentomes near to the cervix using transrectal ultrasonography was easily achieved. There was a significant association between placentome size and gestational age, but between-cow variation in placentome size and growth resulted in poor agreement between placentome size and gestational age. CLINICAL RELEVANCE: Although placentomes can be easily visualised during diagnosis of pregnancy using transrectal ultrasonography, mean placentome size should not be used to estimate gestational age.

An evaluation of the changes in distance from the external sole surface to the distal phalanx in heifers in their first lactation.

Thin soles are a significant cause of lameness in dairy cattle but in most cases the diagnosis is based on subjective assessment. Ultrasonography has been used to more directly estimate sole thickness, but mostly on a one-off basis or over a short period of time. Data over a longer period of time (such as a lactation period) are lacking and there are no descriptions of the normal changes that occur over time and to show how sole thickness at calving relates to thickness later in lactation. This study measured the distance between the external sole surface and the distal phalanx (DP) in 25 mixed breed (Jersey cross Friesian and Friesian) heifers on five occasions over their first lactation (approximately 10, 60, 110, 160 and 220 days post calving). There was a significant effect of claw (medial/lateral) and of time after calving on DP. Mean DP was highest on day 10 and was lowest on day 110 at the tip of the distal phalanx (S1) and on day 160 25 mm towards the heel from the tip (S2). DP was greater at S1 in medial claws and S2 in lateral claws. Although mean DP decreased between days 10 and 110, this change was correlated to DP at day 10. At S1 claws with a DP of <7.5mm tended to increase in thickness between day 10 and 110. Claws which were ≤ 8.25 mm at day 10 were 2.43 (95% CI 0.86-6.89) times more likely to be thin (<7.0mm) at day 110, but of the 12 thin claws at day 110, six had had an adequate DP (>8.25 mm) at day 10. A single measurement of DP at calving was not an effective method for predicting which claws would became thin during lactation.

Causes of abortion on New Zealand dairy farms with a history of abortion associated with Neospora caninum.

AIM: To investigate the cause of abortion in cows from farms with a history of abortion associated with Neospora caninum. METHODS: Cows and primiparous heifers (n = 2,246) that were enrolled in a clinical trial of a vaccine for N. caninum, and 403 cows and heifers that conceived >6 weeks after the planned start of mating (PSM), were monitored for abortion on five dairy farms with a history of abortion associated with N. caninum. When abortion was detected the fetus and/or placenta were submitted for histopathological examination and maternal paired sera were collected for the detection of antibodies to N. caninum using the indirect fluorescent antibody test (IFAT), bovine viral diarrhoea virus (BVDV) using ELISA, and Leptospira spp. using the microscopic agglutination test (MAT). RESULTS: At the start of the clinical trial, 189/1,760 (10.7%) of cows and 61/486 (12.6%) of heifers had IFAT titres ≥1:200 for N. caninum. Abortions were detected in 111 (4.9%) enrolled and 37 (9.2%) non-enrolled cows and heifers. The relative risk of abortion was 4.21 (95% CI 2.92-6.08) times greater in enrolled animals that were seropositive to N. caninum than seronegative animals (p < 0.01). Among all animals, histopathological lesions suggestive of protozoal abortion were seen in nine, and of bacterial infection in 15, of the 40 cases where the fetus and/or placenta were recovered. IFAT titres for N. caninum ≥1:1,000 were detected in 66 cows at abortion, including 7/9 cases where there were fetal lesions indicative of N. caninum infection. In nine cows that aborted, there was evidence of seroconversion to BVDV and eight cows had MAT titres for Leptospira spp. ≥1:200. Histopathology revealed dual infectious aetiologies in two cases and, in another 17 cases, there was serological evidence of recent exposure to a second infectious agent capable of causing abortion in conjunction with N. caninum lesions in the fetus or fetal bacteraemia. CONCLUSIONS: Multiple infectious aetiologies occur at herd-level and in individual cows on farms with a history of abortion associated with N. caninum. A diagnosis of abortion due to N. caninum infection was made in 9/34 (26.5%) cases where fetal histopathology was undertaken. CLINICAL RELEVANCE: Thorough and ongoing diagnostic investigations should be undertaken in herds with higher than expected abortion losses to identify all causative agents as control measures could be implemented that may also reduce the risk of abortion in cows infected with N. caninum.

Uterine environment as a regulator of birth weight and body dimensions of newborn lambs.

Pure-bred embryos were transferred within and reciprocally between large (Suffolk) and small (Cheviot) breeds of sheep to establish 4 treatment groups: SinS (Suffolk embryos in Suffolk dams), SinC (Suffolk embryos in Cheviot dams), CinS (Cheviot embryos in Suffolk dams), and CinC (Cheviot embryos in Cheviot dams). The recipient ewes carried single fetuses to term. The maternal plasma concentrations of ovine placental lactogen (oPL), progesterone, IGF-1, FFA, and glucose were measured on d 50, 90, 120, and 140 of pregnancy. Birth weight, body dimensions, and placental characteristics of lambs were recorded at birth. There was a recipient ewe breed × lamb breed × time interaction for the concentration of oPL (P = 0.03), but no such interaction was observed for progesterone (P = 0.42), IGF-1 (P = 0.57), glucose (P = 0.36), or FFA (P = 0.72). There were no differences in oPL (P = 0.28) and progesterone (P = 0.34) concentrations between SinC and SinS ewes. The concentrations of FFA on d 140 (P = 0.008), and those of glucose on d 50 (P = 0.02) and 120 (P = 0.01), were greater in SinC ewes than in SinS ewes. The ewes in CinS had less FFA concentration (P = 0.002) at all time points than CinC ewes. The concentrations of IGF-1 on d 90 were greater (P = 0.004) in CinS ewes than CinC ewes, but did not differ (P = 0.16) on d 50, 120, and 140. The concentrations of glucose on d 50 (P = 0.001), 90 (P = 0.03), and 140 (P = 0.03) were less in CinS ewes compared with CinC ewes. The birth weight of SinC lambs (5.04 ± 0.20 kg) was lighter (P = 0.001) than SinS lambs (5.94 ± 0.19 kg), and body dimensions of SinC lambs were smaller (P = 0.01) than SinS lambs. Neither birth weight nor the body dimensions of CinS lambs differed (P = 0.24) from CinC lambs. Cotyledon number was reduced (P = 0.04) in the CinS (57.5 ± 6.3) compared with the SinS group (74.2 ± 5.9), whereas mean cotyledon weight in CinS (2.42 ± 0.20 g) was greater (P = 0.02) than SinS (1.74 ± 0.21 g). It was concluded that the large genotype lambs were lighter and smaller when born to small genotype dams; however, the birth weight or body dimensions of small genotype lambs did not differ when born to large genotype dams. This study suggests that plasma oPL, progesterone, IGF-1, FFA, and glucose concentrations at different times throughout pregnancy reflect the regulatory effect of the uterine environment on the development of the fetus.

Culture results from milk samples submitted to veterinary diagnostic laboratories from August 2003 to December 2006 in New Zealand.

AIMS: To determine the pattern of isolation of major mastitis-causing organisms isolated from milk samples submitted to five veterinary diagnostic laboratories in New Zealand. METHODS: The culture results of 25,288 milk samples that were collected from dairy cows throughout New Zealand from August 2003 to December 2006 and submitted to a group of veterinary diagnostic laboratories were assembled, reviewed and summarised. Logistic regression was used to analyse the effect of year, region (i.e. North vs South Island), and season on the probability of isolating the two most common organisms. RESULTS: The most commonly isolated mastitis causing organisms from all samples were: Streptococcus uberis (23.6%), Staphylococcus aureus (23.5%), coagulase-negative staphylococci (CNS; 7.2%), Strep. dysgalactiae (6.2%), Bacillus spp. (4.0%), and coliforms (3.7%). The percentage of samples with isolates of Strep. uberis or Staph. aureus was affected by island, year and season (p<0.001). For most of the year, except in late winter and early spring when Strep. uberis was much more common, the percentage of isolates of Strep. uberis and Staph. aureus were not apparently different despite the former being an environmental pathogen and the other a contagious one. CONCLUSION: The pattern of isolation of major mastitis-causing organisms, as determined from culture of milk samples submitted to diagnostic laboratories in New Zealand, has changed significantly over the last 40 years, with a substantial increase in the percentage of isolates that are Strep. uberis and a decrease in isolates of Strep. agalactiae. There is a clear seasonal pattern to the isolation of both Strep. uberis and Staph. aureus, particularly the former. CLINICAL RELEVANCE: Knowledge of the aetiological agents causing bovine mastitis on a farm is of value in determining the choice of treatment. This dataset shows that, although there is seasonal pattern to the isolation of mastitis-causing organisms in New Zealand, both Strep. uberis and Staph. aureus are isolated throughout the year, so bacteriology is of value in determining aetiology even in late winter/early spring.

Efficacy of a novel internal dry period teat sealant containing 0.5% chlorhexidine against experimental challenge with Streptococcus uberis in dairy cattle.

The incidence of clinical mastitis and infection status at calving was assessed in quarters treated with 1 of 2 internal teat sealants at the time of dry off. Two contralateral quarters per cow (n=63 cows) were treated with a sealant that contained 0.5% chlorhexidine; the other quarters were treated with a commercial teat sealant. Ten cows were untreated (controls). On d 2, 4, and 16 after dry off, cows were challenged with Streptococcus uberis S210 strain. Cows were examined daily for 34 d after drying off and cases of clinical mastitis were recorded. Milk samples were collected for culture from any quarters that developed clinical mastitis during the first 34 d after drying-off and from all quarters on d -5 and 0 relative to treatment and at the first and twentieth milking after calving. The incidence of clinical mastitis during the examination period was lower in treated quarters (n=7/252; 1.5%; lower incidence for those treated with chlorhexidine-containing teat sealant n=3/126; 1.2%) than in untreated quarters (n=13/40; 26.8%). The protection against intramammary infection after calving, adjusted for the effect of cow, was higher in quarters treated with the novel teat sealant (89/105; 15.2%; 95% CI=9.6-23.4) than in those treated with the commercial teat sealant (71/104; 31.7%; 95% CI=23.5-41.3) and untreated controls (6/28; 78.6%; 95% CI=59.8-90.0), respectively. Quarters treated with teat sealants were less likely to have an intramammary infection after calving and had a lower incidence of clinical mastitis during the early dry period than did untreated controls in this challenge study.

Rams genetically superior for IGF-I do not exhibit improved male reproductive traits.

Insulin-like growth factors (IGFs) play an important role in regulating normal physiology, and may be involved in the control of reproduction. The aim of this study was to define the relationship between IGF-I concentrations and reproductive performance over the breeding and non-breeding seasons in lines of New Zealand Romney rams that had been selected for low and high blood serum IGF-I concentration. Yearling rams from two selection lines (13 from the high line and 19 from the low line) were examined in July (winter), September (autumn) and November (summer) 2006 and March (spring) 2007. Scrotal circumference including the inguinal skin was recorded. Semen was collected by electroejaculation on 4 occasions over a 12-month period. Semen was evaluated according to standard procedures (volume, motility, density and morphology). Samples were collected from four animals from each group for measurements of mRNA for IGF-I and the IGF type 1 receptor (IGF 1R) in the testis, and IGF-I, IGF 1R and the insulin receptor (IR) in the liver. Blood samples were collected via jugular venipuncture for the measurement of IGF-I, insulin and testosterone. The incidences of morphologically abnormal sperm cells, the scrotal circumference and sperm motility were higher in the breeding than in non-breeding season. Seasonal changes were found in the percentage of abnormal sperm, scrotal circumference, sperm motility and sperm density, but there were no differences between lines in any reproductive parameters. IGF-I mRNA levels were higher in the high than the low line in the liver but not in the testis, whereas the opposite was found for levels of IGF 1R mRNA. mRNA levels for the insulin receptor in the liver were higher in the high line. Plasma testosterone concentrations did not differ between lines, whereas the concentrations of IGF-I and insulin were higher in the high line. The results suggest that IGF-I may be locally produced in the liver and the testis, and that selection for high IGF-I may not be associated with improved reproductive performance in rams.

Transcutaneous ultrasound over the right flank to diagnose mid- to late-pregnancy in the dairy cow.

OBJECTIVE: To investigate the practical application and image quality of transcutaneous ultrasonography across the right flank for the diagnosis of mid- to late-gestation in cattle. PROCEDURE: Dairy cows of known pregnancy status were used to establish criteria for the identification of mid- to late-stage pregnancy by transcutaneous ultrasonography. Factors involved in the practical application of transcutaneous ultrasound for routine use in pregnancy diagnosis in dairy cattle were also examined. RESULTS: Transcutaneous ultrasound, using a 3.5-MHz sector transducer applied over the caudodorsal right flank fold, allowed rapid and detailed visualisation of bovine pregnancy (i.e. fetus, fetal fluids, placentomes and/or fetal membranes) and could be used to establish criteria for the diagnosis of pregnancy. The commonly available cattle holding facilities of the herringbone dairy, rotary herringbone dairy, AI race or crush, and walk-through dairy all allow safe access to the right flank of a dairy or beef cow. However, transcutaneous scanning over the right flank is difficult in modern rotary turnstile dairies. CONCLUSION: A 3.5-MHz sector transducer applied over the caudodorsal right flank fold allows detailed visualisation of the bovine fetus in most types of cattle-holding facilities. Further investigation of the sensitivity and specificity of this technique over the entire gestation period and its possible use in ageing of the bovine fetus is merited.

Comparison of transcutaneous ultrasound over the right flank with transrectal ultrasound for pregnancy diagnosis in the dairy cow.

OBJECTIVE: Evaluate the sensitivity and specificity of transrectal ultrasound and transcutaneous ultrasonography across the right flank between days 31 and 196 of pregnancy in the dairy cow. PROCEDURE: Pregnancy status and stage of gestation at date of pregnancy diagnosis by transcutaneous and transrectal ultrasonography were determined for 1570 dairy cattle. Sensitivity and specificity values and probabilities of a correct diagnosis for both techniques were determined and compared. Possible effects of gestational age, herd, method of transcutaneous ultrasound diagnosis, cow age, cow and bull breed, and calf sex on the determination of a correct diagnosis of pregnancy status were evaluated for both techniques. RESULTS: The overall sensitivity and probability of a correct diagnosis of pregnancy status from days 31 to 196 of gestation were significantly higher when using transrectal ultrasound relative to transcutaneous ultrasound over the right flank. However, the sensitivity of transcutaneous ultrasound changed over the course of pregnancy: it was low (7-8%) before day 84, increased to 89% between days 141 and 154, and was close to 100% thereafter. The specificity of both methods did not differ significantly. Herd and gestational age at date of pregnancy diagnosis were significantly associated with making a correct test result using transcutaneous ultrasound, although only the latter predictor was significantly associated with making a correct test result using transrectal ultrasound. CONCLUSION: Transcutaneous ultrasound can not be recommended as an accurate method for early pregnancy diagnosis in the dairy cow, particularly on a whole-herd basis. However, if pregnancy testing is undertaken in mid to late gestation, this technique could provide an accurate and rapid alternative to transrectal ultrasound or manual palpation per rectum.

Association between gestational age and bovine fetal characteristics measured by transcutaneous ultrasound over the right flank of the dairy cow.

OBJECTIVE: To determine bovine fetal characteristics significantly associated with increasing gestational age as measured via transcutaneous ultrasonography over the right flank. METHODS: The length of gestation at date of pregnancy diagnosis via transcutaneous and transrectal ultrasonography was determined for 224 dairy cattle by estimation from subsequent calving dates. A separate dataset was created for each measurable fetal characteristic (i.e. thoracic diameter, abdominal diameter, umbilical diameter, placentome length and placentome height) and risk factors significantly associated with gestational age at pregnancy diagnosis within each dataset, including the fetal characteristic, were identified. RESULTS: Abdominal diameter was the most frequently observed fetal characteristic and thoracic diameter was the least. Gestational age at pregnancy diagnosis (d) was significantly associated with fetal thoracic diameter (P < 0.01), abdominal diameter (P < 0.01) and umbilical diameter (P = 0.02) when measured via transcutaneous ultrasound. Within each model, sire breed, dam breed, dam age and/or calf sex were also significantly associated with gestational age. Gestational age at pregnancy diagnosis was not significantly associated with either placentome height or length (P > 0.05). CONCLUSION: Fetal thoracic diameter, abdominal diameter and umbilical diameter were found to be significantly associated with gestational age between approximate days 73 to 190 of gestation. Transcutaneous ultrasonography may prove a useful method of estimating gestational age in the absence of accurate breeding records.

The incidence and aetiology of clinical bovine mastitis on 14 farms in Northland, New Zealand.

AIM: To estimate the incidence of clinical mastitis and the frequency of isolation of mastitis-causing organisms from clinical cases in one lactation season (July 2005 to May 2006) on 14 dairy farms from the Northland region of New Zealand. METHODS: Cases of clinical mastitis were determined by trained farm personnel who recorded the identity of affected cows. Pooled milk samples from affected quarter(s) were aseptically collected by the farm personnel, for microbiology. Mean numbers of affected cows and quarters were compared at the population and farm level per 305 cow-days-at-risk (DAR). RESULTS: One or more cases of clinical mastitis occurred in 559/3,765 (14.8%) lactating cows. The average incidence of clinical mastitis was 0.19 cases per 305 DAR. The incidence in rear quarters (56.2%) was 1.3 times (p=0.027) that of front quarters (43.8%). The incidence of clinical mastitis and numbers of affected quarters were significantly influenced by the stage of lactation (higher in early lactation), age (higher in older cows) and farm. At the cow level, the most common isolates were Staphylococcus aureus (23.7%) and Streptococcus uberis (23.3%). No causative organisms were identified in 19.9% of the samples. Each cow had an average of 1.8 quarters affected during a case of clinical mastitis. CONCLUSIONS: This study demonstrated a higher incidence of staphylococcal clinical mastitis on dairy farms from Northland than has been reported in other regions of New Zealand.