New Zealand veterinary journal最新文献

{"title":"The effect of parenteral vitamin B₁₂ on the growth rate of dairy calves over the summer and autumn on seven farms from the Central Plateau, New Zealand.","authors":"M Gibson, K E Lawrence, C Balcomb, R A Laven","doi":"10.1080/00480169.2023.2254729","DOIUrl":"10.1080/00480169.2023.2254729","url":null,"abstract":"<p><strong>Aims: </strong>To investigate the effect of parenteral vitamin B₁₂ supplementation on the growth rate of dairy heifer calves over the summer and autumn on seven farms from the Central Plateau of New Zealand, an area historically associated with low cobalt levels in grazing pasture.</p><p><strong>Methods: </strong>This was a controlled clinical trial conducted on a convenience sample of seven farms with young female calves randomly assigned to three vitamin B₁₂ treatment groups and followed through a grazing season. Two treatment groups received either monthly SC injections of a short-acting (SA) B₁₂ formulation or 3-monthly injections of a long-acting (LA) B₁₂ formulation and the third group received no treatment (NT). No additional parenteral vitamin B₁₂ was given; however, all calves received additional cobalt (0.04-0.4 mg Co/kg liveweight) in the mineralised anthelmintic drenches given orally every month. Liveweight was recorded in December/January and at the end of the trial in May/June/July depending on farm. Pasture cobalt concentrations (mg/kg DM) were measured every month using 500-g herbage samples from 100-m transects in the area about to be grazed by the trial groups.</p><p><strong>Results: </strong>There was evidence for a difference in growth rate between groups with mean final weight of 228 (95% CI = 212-243) kg for the LA groups, 224 (95% CI = 209-239) kg for the SA groups and 226 (95% CI = 211-241) kg for the NT groups respectively, (global p-value = 0.014). Calves given SA vitamin B₁₂ were 3.77 (95% CI = 0.71-6.82) kg lighter than calves given LA vitamin B₁₂ (p = 0.011). There was no evidence for a change in pasture cobalt concentrations (p = 0.32).</p><p><strong>Conclusions and clinical relevance: </strong>The results of this trial raise the question as to whether the routine use of vitamin B₁₂ supplementation in young cattle from areas traditionally thought to be cobalt deficient is necessary, and further raise the possibility that vitamin B₁₂ supplementation by repeated injection of SA products may negatively impact growth rates.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":" ","pages":"10-16"},"PeriodicalIF":1.4,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10161299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Re: Pharmacokinetics and effect on renal function and average daily gain in lambs after castration and tail docking, of firocoxib and meloxicam.","authors":"James Laidlaw","doi":"10.1080/00480169.2023.2253580","DOIUrl":"10.1080/00480169.2023.2253580","url":null,"abstract":"","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":" ","pages":"61"},"PeriodicalIF":1.4,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10577227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomechanical comparison of titanium alloy additively manufactured and conventionally manufactured plate-screw constructs.","authors":"S Polak, L Beever, A Wade, M Fukuoka, A J Worth","doi":"10.1080/00480169.2023.2264805","DOIUrl":"10.1080/00480169.2023.2264805","url":null,"abstract":"<p><strong>Aim: </strong>To biomechanically compare the bending stiffness, strength, and cyclic fatigue of titanium additively manufactured (AM) and conventionally manufactured (CM) limited contact plates (LCP) of equivalent dimensions using plate-screw constructs.</p><p><strong>Methods: </strong>Twenty-four 1.5/2.0-mm plate constructs (CM: n = 12; AM: n = 12) were placed under 4-point bending conditions. Data were collected during quasi-static single cycle to failure and cyclic fatigue testing until implants plastically deformed or failed. Bending stiffness, bending structural stiffness, and bending strength were determined from load-displacement curves. Fatigue life was determined as number of cycles to failure. Median test variables for each method were compared using the Wilcoxon rank sum test within each group. Fatigue data was also analysed by the Kaplan-Meier estimator of survival function.</p><p><strong>Results: </strong>There was no evidence for a difference in bending stiffness and bending structural stiffness between AM and CM constructs. However, AM constructs exhibited greater bending strength (median 3.07 (min 3.0, max 3.4) Nm) under quasi-static 4-point bending than the CM constructs (median 2.57 (min 2.5, max 2.6) Nm, p = 0.006). Number of cycles to failure under dynamic 4-point bending was higher for the CM constructs (median 164,272 (min 73,557, max 250,000) cycles) than the AM constructs (median 18,704 (min 14,427, max 33,228) cycles; p = 0.02). Survival analysis showed that 50% of AM plates failed by 18,842 cycles, while 50% CM plates failed by 78,543 cycles.</p><p><strong>Conclusion and clinical relevance: </strong>Additively manufactured titanium implants, printed to replicate a conventional titanium orthopaedic plate, were more prone to failure in a shorter fatigue period despite being stronger in single cycle to failure. Patient-specific implants made using this process may be brittle and therefore not comparable to CM orthopaedic implants. Careful selection of their use on a case/patient-specific basis is recommended.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":" ","pages":"17-27"},"PeriodicalIF":1.4,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41138597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deaths due to suspected hypothermia in sheep and alpacas on a Manawatū farm in New Zealand in mid-summer.","authors":"A L Ridler, E L Gulliver, F Castillo-Alcala","doi":"10.1080/00480169.2023.2251425","DOIUrl":"10.1080/00480169.2023.2251425","url":null,"abstract":"<p><strong>Case history: </strong>In mid-summer (February), 42 of a flock of 68 ram hoggets (approximately 5 months of age) and two of a group of 14 alpacas on a farm in the Manawatū region of New Zealand were found recumbent or dead following a period of persistent rain, strong winds and relatively low temperatures. The hoggets and alpacas had been shorn 4 and 53 days previously, respectively, and were in adequate to good body condition with access to <i>ad libitum</i> pasture. Post-mortem and histological examinations were undertaken on four hoggets and two alpacas.</p><p><strong>Clinical findings: </strong>Apart from hypothermic body temperatures from four recumbent hoggets, nothing of significance was identified on clinical or gross pathological examination. Histological changes of vacuolar hepatopathy, renal tubular degeneration and pulmonary congestion were present in all animals examined.</p><p><strong>Diagnosis: </strong>Based on the history and clinical and pathological findings, hypothermia was highly probable to have been the cause of the deaths.</p><p><strong>Clinical relevance: </strong>These cases emphasise the importance of shelter for recently shorn sheep and alpacas regardless of the season.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":" ","pages":"39-44"},"PeriodicalIF":1.4,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10244560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the effect of prophylactic claw trimming on the interval between calving and first observed elevated locomotion score in pasture-based dairy cows.","authors":"C W Werema, F Hoekstra, L J Laven, K R Müller, D Gifford, R A Laven","doi":"10.1080/00480169.2023.2238654","DOIUrl":"10.1080/00480169.2023.2238654","url":null,"abstract":"<p><strong>Aims: </strong>To evaluate, in a pasture-based dairy herd, the response to a three-time point hoof trimming regime on lameness incidence and time from calving to observation of an elevated locomotion score (LS).</p><p><strong>Methods: </strong>This study was conducted on a 940-cow spring-calving herd in New Zealand's North Island between May 2018 and May 2019. Cows (n = 250) were randomly allocated to the hoof trimming group, with the remainder assigned to the non-trim cohort. One trained professional hoof trimmer used the five-step Dutch method to trim the hind feet of the trimming group. Throughout the subsequent production season, the whole herd was locomotion-scored fortnightly using the 4-point (0-3) Dairy NZ lameness score. Kaplan-Meier survival curves were used to assess the univariable effect of trimming on the interval between calving and first LS of ≥ 2 and first LS ≥ 1. A multivariable Cox proportional hazards regression was used to further evaluate the effect of trimming on time to elevated LS.</p><p><strong>Results: </strong>Mean lameness (LS ≥ 2) prevalence was 2.6%, with 30% of cows having ≥ 4 observations during the study period when at least one LS was ≥ 2. For LS ≥ 1, mean prevalence was 40%, with 98.6% of cows having ≥ 4 observations during the study period when at least one LS was ≥ 1 during lactation. Hoof trimming had no apparent effect on the incidence of clinical lameness (LS ≥ 2) (trimmed <i>vs.</i> non-trimmed: 33.2% <i>vs.</i> 28.8%, respectively), but for LS ≥ 1, there was a small decrease in the incidence of LS ≥ 1 (trimmed <i>vs.</i> non-trimmed: 96.9% <i>vs</i>. 99.3%, respectively). The hazard of a cow having a first observed LS ≥ 2 in the control group was 0.87 (95% CI = 0.66-1.14) times that of the trimmed group; however, the hazard of a cow having a first LS ≥ 1 was 1.60 (95% CI = 1.37-1.88) times higher in the control than in the trimmed group.</p><p><strong>Conclusion and clinical relevance: </strong>On this farm, prophylactic hoof trimming had no clinically relevant impact on the incidence of clinical lameness and was not associated with clinically beneficial reductions in time to first observed LS ≥ 2. This may be because claw horn imbalance was not pronounced on this farm, with 53% of cows needing no trim on either hind limb on the first trimming occasion. Further research on the response to prophylactic trimming in pasture-based dairy cattle is required.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":" ","pages":"295-305"},"PeriodicalIF":1.4,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10336049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mammary tubulopapillary carcinoma in a mare, requiring bilateral mastectomy.","authors":"C P Beggan,&nbsp;G C Quinn,&nbsp;G H D'Amours","doi":"10.1080/00480169.2023.2246932","DOIUrl":"https://doi.org/10.1080/00480169.2023.2246932","url":null,"abstract":"Mammary neoplasia is uncommon in the mare and often mistaken for mastitis (Reppas et al. 1996). Incidence rates of mammary tumours in horses of 0.1–1.9% are reported, with carcinomas the most common (Brito et al. 2008). Due to the low incidence, and similarity of initial signs to those of mastitis, diagnosis is often delayed until after antibiotic and antiinflammatory treatment has failed (Boyce and Goodwin 2017). Mares are often, therefore, presented in an advanced stage of disease with a poor prognosis (Ferreira Júnior et al. 2019). Due to the infrequency of mammary neoplasia in horses it has been difficult to develop an evidence based approach to treatment. Studies in domestic animals report a low success rate with conservative management of these neoplasms. Combined with their highly aggressive and metastatic nature, surgical excision has been perceived as the treatment of choice in the initial management of these neoplasms (Seahorn et al. 1992). Mammary tubulopapillary carcinomas have been reported in multiple species, including horses. They are more malignant than other forms of mammary carcinoma; lymphovascular and lymph node metastasis occurs commonly (Goldschmidt et al. 2016). This case report describes the surgical treatment of a mare with advanced bilateral mammary tubulopapillary carcinoma and describes the use of a barbed wound closure device to reduce surgical dead space to aid in complete wound closure. An 18-year-old, Thoroughbred, multiparous, barren mare was presented to the referring veterinarian with an enlarged left mammary gland during a routine reproduction examination. Over the next 3 months the mare received three courses of anti-inflammatory drugs and antibiotic therapy based on culture and sensitivity, but clinical signs persisted. The left mammary gland was scanned, revealing a mass in the interstitial tissue. The mare was then referred for further investigation, 3.5 months after initial presentation. On presentation, the mare underwent a general physical examination, the results of which were within normal limits except that the left mammary gland was enlarged and firm, with three ulcerative lesions (Figure 1A). No pain response was elicited upon palpation. The teat was also firm and enlarged. Palpation of the right gland revealed some firm masses throughout, with a normal teat. Serosanguinous secretions were easily expressed from each teat. A jugular blood sample was submitted for routine haematology and biochemistry (including serum amyloid A) and all parameters were within normal limits. Ultrasound examination of both glands was performed using a 2–5 MHz curved array transducer. The left gland and teat revealed extensive areas of mixed echogenicity with microlobulated margins and an abrupt interface between the mass and normal mammary tissue in some areas (Figure 1B) with more diffuse and generalised margins elsewhere. The right gland contained multiple focal areas of mixed echogenicity with microlobulated margins,","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":"71 6","pages":"344-347"},"PeriodicalIF":1.4,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41207358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Persistence of orthopaedic hoof blocks for the treatment of lame cattle kept permanently at pasture.","authors":"K R Müller,&nbsp;R A Laven,&nbsp;L J Laven","doi":"10.1080/00480169.2023.2216658","DOIUrl":"https://doi.org/10.1080/00480169.2023.2216658","url":null,"abstract":"<p><strong>Aims: </strong>To compare the retention by New Zealand dairy cows kept at pasture in a lame cow group, of three hoof block products commonly used in the remediation of lameness.</p><p><strong>Methods: </strong>Sixty-seven farmer-presented Friesian and Friesian x Jersey dairy cows from a single herd in the Manawatū region (New Zealand) suffering from unilateral hind limb lameness attributable to a claw horn lesion (CHL) were randomly allocated to one of three treatments: foam block (FB), plastic shoe (PS) and a standard wooden block (WB). Blocks were applied to the contralateral healthy claw and checked daily by the farm staff (present/not present) and date of loss was recorded. Blocks were reassessed on Day 14 and Day 28 and then removed unless further elevation was indicated. Daily walking distances were calculated using a farm map and measurement software. Statistical analyses included a linear marginal model for distance walked until block loss and a Cox regression model for the relative hazard of a block being lost.</p><p><strong>Results: </strong>Random allocation meant that differences between products in proportion used on left or right hind foot or lateral or medial claw were small. Mean distance walked/cow/day on farm tracks whilst the block was present was 0.32 (min 0.12, max 0.45) km/day; no biologically important difference between products in the mean distance walked was identified. Compared to PS, cows in the WB group were five times more likely to lose the block (HR = 4.8 (95% CI = 1.8-12.4)), while cows in the FB group were 9.5 times more likely to lose the block (HR = 9.5 (95% CI = 3.6-24.4)).</p><p><strong>Conclusions: </strong>In this study, PS were retained for much longer than either FB or WB. As cows were managed in a lame cow group for the study duration, walking distances were low and did not impact on the risk of block loss. More data are needed to define ideal block retention time.</p><p><strong>Clinical relevance: </strong>In cows with CHL the choice of block could be based on the type of lesion present and the expected re-epithelisation times.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":"71 5","pages":"236-243"},"PeriodicalIF":1.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10323279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of intraocular pressure in New Zealand White rabbits measured using rebound and applanation tonometers and four different methods of physical restraint.","authors":"S Okur, L E Yanmaz, M G Senocak, U Ersöz, A Gölgeli, F Turgut, O T Orhun, Y Kocaman","doi":"10.1080/00480169.2023.2224277","DOIUrl":"10.1080/00480169.2023.2224277","url":null,"abstract":"<p><strong>Aims: </strong>To compare intraocular pressure (IOP) measurements obtained in rabbits using rebound (TV) and applanation (TPV) tonometers with four different methods of physical restraint.</p><p><strong>Methods: </strong>A total of 20 New Zealand White rabbits (40 eyes) were included in this study. IOP readings were obtained from both eyes using the two different tonometers. The rabbits were placed on a table and restrained by wrapping in a cloth (Method I), by scruffing with rear support (Method II), by wrapping in a cloth and cupped in the hands (Method III), or by a box restrainer (Method IV).</p><p><strong>Results: </strong>The mean IOP measurement obtained by TPV was higher than that obtained with the TV for all handling methods. Mean differences (TV-TPV, in mmHg) in IOP were -5.3 (95% Cl = -6.5 to -4.1) for Method 1, -4.7 (95% Cl = -6.2 to -3.29) for Method II, -4.9 (95% Cl = -6.2 to -3.7) for Method III and -7.6 (95% Cl = -9.2 to -5.9) for Method IV. Using the TV tonometer, mean IOP for Method IV was higher than for Method I (mean difference 2.1 (95% Cl = 1.1-3.1)), whereas using the TPV tonometer, mean IOP for Method IV was significantly higher than Method I, II, and III (mean differences: 4.4 (95% Cl = 2.6-5.9), 3.7 (95% Cl = 2-5.3) and 3.8 (95% Cl = 2-5.4), respectively). According to Bland-Altman plots, IOP readings for TPV tended to be higher than those for TV with all handling methods, but with a lack of agreement. The mean difference and 95% limits of agreement for the differences between TV and TPV were -5.4 mmHg (-12.5-1.9 mmHg), -4.7 mmHg (-12.9-3.5 mmHg), -4.9 mmHg (-12-2.2 mmHg), and -7.5 mmHg (-17.4-2.3 mmHg), with Methods I, II, III, and IV, respectively. Comparing TV and TPV, only 7.5%, 12.5%, 27.5%, and 15% of IOP measurements from 20 rabbits were within the range considered clinically acceptable for IOP (± 2 mmHg) for Method I, II, III, and IV, respectively.</p><p><strong>Conclusion and clinical relevance: </strong>In conclusion, the physical restraint method should be recorded when IOP is measured in rabbits, and TV and TPV tonometers cannot be used interchangeably (high bias and low proportion of measurements within ± 2 mmHg).</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":"71 5","pages":"251-258"},"PeriodicalIF":1.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9972976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of common sedation agents on feline splenic size determined via ultrasonography.","authors":"E Short,&nbsp;J Chagas,&nbsp;M Kurihara,&nbsp;Y Ishikawa,&nbsp;J P Chambers,&nbsp;J Bridges,&nbsp;H Sano","doi":"10.1080/00480169.2023.2223177","DOIUrl":"https://doi.org/10.1080/00480169.2023.2223177","url":null,"abstract":"<p><strong>Aims: </strong>To evaluate the effect of IM administration of three sedative drugs, acepromazine, alfaxalone and dexmedetomidine, in combination with morphine, on the size of the feline spleen using ultrasonography.</p><p><strong>Methods: </strong>Twenty-four client-owned cats undergoing elective de-sexing or minor procedures were recruited for a focused ultrasonographic examination of the spleen prior to and at 10, 20 and 30 minutes following administration of one of three randomly assigned IM sedation protocols: 0.05 mg/kg acepromazine (ACE group), 3 mg/kg alfaxalone (ALF group), or 10 μg/kg dexmedetomidine (DEX group), in combination with 0.5 mg/kg morphine. B-mode images of the spleen were collected and measured following a standardised protocol. Cardiorespiratory parameters and sedation score were also recorded. Mean thickness of the head, body and tail of the spleen for each group at 10, 20 and 30 minutes after drug administration was compared to baseline.</p><p><strong>Results: </strong>Mean splenic thickness increased over time in the ACE group (thickness of body at T0 = 8.9 (SE 2.1) mm and at T30 = 10.5 (SE 2.0) mm; p = 0.001) and the ALF group (thickness of body at T0 = 8.8 (SE 1.0) mm and at T30 = 10.3 (SE 1.7) mm; p = 0.022) but not in the DEX group (thickness of body at T0 = 8.6 mm (1.2) and at T30 = 8.9 mm (0.6); p = 0.67). Mean arterial blood pressure in the DEX group was significantly higher than in the other groups (p = 0.002). Sedation scores in the DEX group were consistently high for the entire period. However, the sedation score in the ACE group increased over 30 minutes (p = 0.007). Sedation score in the ALF group was highest at 10 minutes but gradually decreased over the following 20 minutes (p = 0.003).</p><p><strong>Conclusions: </strong>Sedation with IM dexmedetomidine and morphine did not change splenic size, whereas acepromazine or alfaxalone and morphine increased it regardless of the degree of sedation.</p><p><strong>Clinical relevance: </strong>Where splenomegaly is identified in a cat sedated with acepromazine or alfaxalone, the effects of the sedation protocol could be considered as a possible cause.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":"71 5","pages":"244-250"},"PeriodicalIF":1.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9970655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Animal- and herd-level factors associated with onset of puberty in grazing dairy heifers.","authors":"N M Steele,&nbsp;M A Stephen,&nbsp;B Kuhn-Sherlock,&nbsp;S J Hendriks,&nbsp;S Meier,&nbsp;Cvc Phyn,&nbsp;C R Burke","doi":"10.1080/00480169.2023.2224763","DOIUrl":"https://doi.org/10.1080/00480169.2023.2224763","url":null,"abstract":"<p><strong>Aims: </strong>To explore animal- and herd-level risk factors influencing age at puberty in predominantly Holstein-Friesian dairy heifers managed in seasonal, pasture-based systems.</p><p><strong>Methods: </strong>Heifers born in spring 2018 (n = 5,010) from 54 commercial dairy herds in New Zealand were visited on three occasions when the mean heifer age, within herd, was 10 (visit 1; V1), 11 (V2) and 12 (V3) months old. Blood samples were collected on each visit and liveweight, stature and anogenital distance (AGD) were measured at V2. Heifers were defined as having reached puberty at the first visit where blood progesterone was elevated (≥ 1 ng/mL). Animal-level response variables included pubertal status by V1, V2 and V3, and age at puberty (or age at V3 plus 31 days for those that had not attained puberty by V3). To explore herd-level management factors, farmers answered a questionnaire relating to animal location, land type, health, feeding, and management between weaning and mating. A partial least squares regression was undertaken to identify herd-level factors associated with the greatest influence on puberty rate within herd.</p><p><strong>Results: </strong>The mean age at puberty was 352 (SD 34.9) days. Heavier animals at a greater proportion of expected mature liveweight based on their breeding value for liveweight, or animals with a higher breed proportion of Jersey and lower breed proportion of Holstein, were associated with earlier puberty. Herd puberty rates varied widely among enrolled herds, and averaged 20%, 39% and 56% by V1, V2 and V3, respectively. Liveweight, followed by breed and land type, had the greatest influence on the herd puberty rate. Heifer herds with a greater mean liveweight (absolute and proportion of expected mature weight) or greater Jersey proportion had more animals that reached puberty at any visit, whereas herds located on steep land or with greater Holstein breed proportions had lower puberty rates. Management-related factors such as vaccinations, provision of feed supplements, and weighing frequency were also herd-level risk factors of puberty but had less influence.</p><p><strong>Conclusions and clinical relevance: </strong>This study highlights the importance of having well-grown heifers for increasing the chances of earlier puberty onset and the effect of breed and youngstock management to achieve growth targets. These outcomes have important implications for the optimal management of heifers to achieve puberty before their maiden breeding and for the timing of measurements to potentially incorporate a puberty trait in genetic evaluations.</p>","PeriodicalId":19322,"journal":{"name":"New Zealand veterinary journal","volume":"71 5","pages":"213-225"},"PeriodicalIF":1.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9970711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}