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To use a farm-based survey to identify characteristics of the New Zealand dairy system associated with the risk of spontaneous humeral fracture in dairy heifers. A questionnaire was designed and made available in print and online to collect information from dairy farmers and/or veterinarians, across New Zealand, about the management and nutrition of cows from birth to first lactation. Data were collected from July 2019 to March 2020 from farms that either had recorded (case farms) or not recorded (control farms) cases of humeral fractures in dairy heifers. A total of 68 completed questionnaires were returned, with 35 responses from case farms and 33 responses from control farms. Twenty-six responses (38%) were from the South Island (13 case farms and 13 control farms) and 38 responses (56%) were from the North Island (20 case farms and 18 control farms). For four questionnaires (6%) farm location was not given. Adjusting for the effect of age when calves accessed pasture, case farms had increased odds of having Holstein-Friesian Jersey crossbreed cows as the predominant breed (OR = 9.7; 95% CI = 3.1–36.0; p < 0.001). Adjusting for the effect of breed, allowing calves access to pasture a week later decreased the odds of being a case farm (OR = 0.68; 95% CI = 0.47–0.90; p = 0.006). Cows being Holstein-Friesian Jersey crossbreed was identified as a possible risk factor associated with spontaneous humeral fracture in dairy heifers in New Zealand. Given the small sample size, the likely multifactorial aetiology for humeral fractures, and the non-randomised survey, this risk factor, and the possible association between age at turn out and herd production with humeral fractures, all require further investigation. [ABSTRACT FROM AUTHOR]

Serum and liver samples from 35, 2-year-old dairy heifers that had fractured one or both humeri post-calving between July and December 2019 were submitted to a diagnostic laboratory for analysis. Serum samples were analysed for albumin, β-hydroxybutyrate (BHB), creatinine, Ca, Mg, phosphate, non-esterified fatty acids (NEFA), and serum Cu concentration. Liver samples were analysed for liver Cu concentration. Data were compared to published reference intervals. Data values for heifers that prior to fracture had grazed fodder beet were also compared to values for those that had grazed pasture. Sixty-nine percent of heifers with humeral fracture had serum creatinine concentrations below the lower value of the reference range (55–130 µmol/L). In 3/32 (9%) heifers, serum NEFA concentrations were increased above the reference value indicating body fat mobilisation (≥1.2 mmol/L for peri-partum cows) and in 20/35 (57%) heifers BHB serum concentrations were above the reference value indicating subclinical ketosis (≥1.1 mmol/L for peri-partum cows). In 24/35 (69%) heifers, liver Cu concentration was low (≤ 44 µmol/kg) or marginal (45–94 µmol/kg). The concentration of Cu in serum was low (≤ 4.5 µmol/L) in 2/33 (6%) heifers and marginal (4.6–7.9 µmol/L) in 5/33 (15%) heifers. There was moderate positive correlation between the logged concentrations of Cu in paired liver and serum samples, r(31) = 0.43; (95% CI = 0.1–0.79; p = 0.014). One heifer had a serum phosphate concentration below the lower limit of the reference range (< 1.10 mmol/L). For all heifers, the concentrations of albumin, Ca, and Mg in serum were within the reference intervals (23–38 g/L, 2.00–2.60 mmol/L, and 0.49–1.15 mmol/L respectively). Over winter, 15/35 (43%) heifers grazed predominantly pasture, 14/35 (40%) grazed fodder beet and 6/35 (17%) had a mixed diet. In some of these heifers with humeral fractures, there was evidence for protein and/or energy malnutrition in the form of elevated NEFA and BHB concentrations and low creatinine concentrations in serum. Liver Cu concentrations were also reduced in most affected heifers. However, the absence of a control group means it is not possible to determine if these are risk factors for fracture or features common to all periparturient heifers. Clinical trials and molecular studies are needed to determine the true contribution of Cu and protein-energy metabolism to the pathogenesis of spontaneous humeral fractures in dairy heifers. BHB: ß-hydroxybutyrate; NEFA: Non-esterified fatty acids [ABSTRACT FROM AUTHOR]

Aim: To assess whether the fluoride concentration in the humeri of first-lactation, 2-year-old dairy cows with a spontaneous humeral fracture is significantly different from that of first-lactation, 2-year-old dairy cows without a humeral fracture., Methods: Two studies were conducted, the first with nine bone samples from 2-year-old, first-calving dairy cows with a humeral fracture (all from the Waikato region) age-matched with seven control bone samples from the Waikato, Bay of Plenty and Manawatū-Whanganui regions. The second study used 26 bone samples from 2-year-old, first-lactation dairy cows with a humeral fracture (from the Otago, Canterbury, Southland, West Coast, Waikato and Manawatū-Whanganui regions) age-matched with 14 control bone samples (all from the Manawatū-Whanganui region or unknown). Control bone samples were from first-lactation, 2-year-old dairy cows that did not have humeral fractures. Bone fluoride concentration was quantified for all samples., Results: The median fluoride concentration of humeri from first-lactation, 2-year-old dairy cows with a humeral fracture was significantly higher than humeri from unaffected control cows in both studies. In Study 1, the median bone fluoride concentration was 599 (IQR 562.7-763.5) mg/kg from case cows and 296.6 (IQR: 191.2-391.7) mg/kg from control cows (p < 0.001), and in Study 2 the median bone fluoride concentration from case and control cows was 415 (IQR: 312.5-515) mg/kg and 290 (IQR: 262.5-410) mg/kg (p = 0.04) respectively., Conclusions and Clinical Relevance: Although there are limitations to this study due to the unbalanced regional distribution of cases and controls, the results indicate that sub-clinical fluoride toxicosis may be linked to spontaneous humeral fractures in first-lactation dairy cows in New Zealand. Further research is required to determine if bone fluoride concentrations play a role in the pathogenesis of these fractures.

The occurrence of spontaneous humeral fractures in primiparous dairy cows from New Zealand prompted the study of bone material from affected cows to further characterize this condition and to outline a likely pathogenesis. Previous studies indicate that these cows developed osteoporosis due to periods of suboptimal bone formation followed by increased bone resorption during the period of lactation complicated by copper deficiency. We hypothesized that there are significant differences in the chemical composition/bone quality in bones from cows with spontaneous humeral fracture compared to cows without humeral fractures. In this study, Raman and Fourier transform infrared spectroscopy band ratios were, for the first time, measured, calculated, and compared in bone samples from 67 primiparous dairy cows that suffered a spontaneous fracture of the humerus and 14 age-matched post-calving cows without humeral fractures. Affected bone showed a significantly reduced mineral/matrix ratio, increased bone remodeling, newer bone tissue with lower mineralization and, lower carbonate substitution, and reduced crystallinity. As such, is likely that these have detrimentally impacted bone quality and strength in affected cows., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wehrle-Martinez, Waterland, Naffa, Lawrence, Back, Rogers and Dittmer.)

Outbreaks of humeral fractures in dairy cows have been reported in New Zealand for several years. Gross, histologic, and histomorphometric findings in the humerus from primiparous cows with spontaneous humeral fracture were compared to age-matched control cows. Affected cows had a complete nonarticular spiral fracture of the humerus. Histologically affected humeri had a thicker growth plate with abnormal architecture, thinner cortex with increased abnormal resorption, increased resorption in the distal humerus, decreased trabecular density, abnormal trabecular architecture, presence of growth arrest lines and woven bone formation. Histomorphometry showed reduction in bone volume, trabecular perimeter, and trabecular width. Cows grazed on fodder beet had thicker growth plates with an abnormal appearance compared with cows grazed on pasture, and cows with low/marginal liver copper concentration had more resorption cavities in the distal humerus and thinner cortical bone compared with cows with adequate liver copper concentration. Decreased trabecular density (OR = 249.5), abnormal cortical resorption (OR = 54.2), presence of woven bone formation in the proximal metaphysis (OR = 37.2), and the number of resorption cavities in the distal humerus were significantly associated with a high probability of fracture. Ribs had enlargement of the costochondral junction with fractures in different stages of healing. Histology of the ribs revealed abnormal growth plate appearance, presence of fracture lines, callus tissue, fibrosis, and microfractures. Cows with humeral fracture have osteoporosis due to decreased bone formation and increased bone resorption, likely associated with inadequate feed quality and perhaps copper deficiency leading to a reduction in bone strength and fracture.

Keeping replacement heifers that were the progeny of primiparous cows mated by artificial insemination enhances rates of genetic gain. Previous research has shown that heifers that were the progeny of primiparous cows were lighter at birth and grew at a slower rate to first calving compared with heifers born to multiparous dams. Furthermore, heifers that were heavier before first calving produced more milk than did lighter heifers. This study aimed to determine whether there were body weight, milk production, or reproductive disadvantages for heifers born from primiparous compared with multiparous dams. Data comprised body weight records from 189,936 New Zealand dairy heifers. Dams were allocated to 4 groups according to their age: 2 yr old (n = 13,717), 3 yr old (n = 39,258), 4 to 8 yr old (n = 120,859), and 9 yr or older (n = 16,102). Heifers that were the progeny of 2-yr-old dams were lighter from 3 to 21 mo of age than heifers that were the progeny of 3-yr-old and 4- to 8-yr-old dams. The progeny of 2- and 3-yr-old dams produced similar milk solids yields (± standard error of the mean) during their first lactation (304.9 ± 1.6 and 304.1 ± 1.5 kg, respectively), but more than that of 4- to 8-yr-old dams (302.4 ± 1.5). Furthermore, the progeny of 2-yr-old dams had similar stayabilities to first, second, and third calving to that of the progeny of 4- to 8-yr-old and ≥9-yr-old dams. Reproductive performance, as measured by calving and recalving rates was similar in first-calving heifers of all age-of-dam classes. Additionally, second and third calving rates were similar for the progeny of 2- and 3-yr-old dams. Interestingly, the progeny of dams ≥9 yr old had the lowest milk solids production in first (297.8 ± 1.6 kg), second (341.6 ± 1.8 kg), and third lactations (393.2 ± 2.4 kg). Based on the results of this study, keeping replacements from dams aged 9 yr and over could not be recommended. Furthermore, heifers born to 2-yr-old dams were lighter but produced more milk than heifers from older dams, in addition to having superior genetic merit., (© 2021, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)

This study investigated the relationships between body weight (BW) and stayability, and BW and calving pattern, of 189,936 New Zealand dairy heifers. Heifers were classified into 5 breed groups: Holstein-Friesian (F), Holstein-Friesian crossbred (FX), Jersey (J), Jersey crossbred (JX), and Holstein-Friesian × Jersey crossbred (FJ). Body weight was predicted using Legendre polynomials at 6, 12, and 15 mo of age, and we analyzed their relationships with stayability, calving rate, and re-calving rate over the first 3 calvings. Approximately 92% of heifers calved for the first time at age 2 yr, 76% a second time at 3 yr, and 61% a third time at 4 yr. Heifers that were heavier were more likely to remain in the herd for first, second, and third calving compared with heifers that were lighter. Furthermore, we found positive curvilinear relationships between pre-breeding BW and reproductive performance of dairy heifers. Heifers that were heavier at 6, 12, and 15 mo were more likely to calve early for first calving compared with heifers that were lighter, regardless of breed group. In addition, we found a large range in BW where the probability of calving or re-calving early was high. For example, FJ heifers that were between 255 and 396 kg at 15 mo of age had 21-d calving and re-calving rates above 75 and 70%, respectively. For second and third lactations, however, heifer pre-breeding BW showed only small effects on the 21-d calving and re-calving rates. For heifers that were at the heaviest end of the BW range in the current study, slight declines in stayability and reproductive performance occurred, compared with heifers in the mid-range of BW. Consequently, for heifers that were above average in BW, the benefit of increasing BW before first breeding would be small and might even result in slight declines in stayability and reproductive performance. For heifers that were below average in BW, considerable beneficial effects on stayability and reproductive performance are predicted as a result of improving rearing practices to produce heavier heifers throughout the pre-breeding rearing phase., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

This study investigated the relationships between body weight (BW) and milk production of 140,113 New Zealand dairy heifers. Heifers were classified into 5 breed groups: Holstein-Friesian, Holstein-Friesian crossbred, Jersey, Jersey crossbred, and Holstein-Friesian-Jersey crossbred. Body weights were assessed at intervals of 3 mo from 3 to 21 mo of age and their relationships with first-lactation and accumulated milk production over the first 3 lactations (3-parity) were analyzed. We found positive curvilinear relationships between BW and milk production. The response to an increase in BW was greater for lighter heifers compared with heavier heifers, indicating possible benefits of preferentially feeding lighter heifers to attain heavier BW. Within the age range and BW range studied, an increase in BW was always associated with an increase in first-lactation energy-corrected milk (ECM) and milk solids (milk fat plus milk protein) yield for breed groups other than Holstein-Friesian. For Holstein-Friesian heifers, there was a positive relationship between BW and ECM and milk solids yields for all ages except for 3 mo of age, when no relationship existed. These results show the potential to increase first-lactation milk production of New Zealand dairy heifers by increasing heifer BW. Likewise, for 3-parity accumulated yields, the BW at which maximum ECM and milk solids yields occurred were at the heavier end of the BW range studied. The costs of rearing a heifer are incurred regardless of how long she remains in the herd. Potential bias exists from considering only cows that survived to lactate each year if particular cows had better survival than others. Therefore, the data in the current study for 3-parity production includes all heifers that were old enough to have completed 3 lactations, regardless of whether they did or not. Including the heifers that did not complete all 3 lactations describes the effect that BW of replacement heifers has on accumulated milk yields without discriminating whether the increased milk yield came from greater survival or from greater production per surviving cow. Further research on the relationships between BW and survival of heifers is required to confirm whether the heavier heifers survived longer than the lighter heifers, but could explain why the relationship between BW and 3-parity milk yields was more curvilinear than the relationship between BW and first-lactation milk production. Holstein-Friesian heifers that were 450 kg in BW at 21 mo of age were estimated to produce 168 and 509 kg more ECM than 425-kg Holstein-Friesian heifers in first-lactation and 3-parity accumulated yields, respectively. A further increase in BW at 21 mo of age, from 450 to 475 kg, was estimated to result in 157 and 409 kg more ECM in first-lactation and 3-parity accumulated yields, respectively. Consequently, for heifers that were average and below average in BW, considerable milk production benefits would occur over the first 3 lactations by improving rearing practices to result in heavier heifers throughout the precalving phase., (The Authors. Published by FASS Inc. and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)

The present study evaluated the effect of controlled ryegrass-white clover herbage availability from day 128 until day 142 of pregnancy in comparison to unrestricted availability, on the performance of twin-bearing ewes of varying body condition score (BCS; 2.0, 2.5, or 3.0) and their lambs. It was hypothesised that under conditions of controlled herbage availability, the performance of lambs born to ewes with a greater BCS would be greater than those born to ewes with a lower BCS. During the period that the nutritional regimens were imposed, the pre- and post-grazing herbage masses of the Control regimen (1,070±69 and 801±30 kg dry matter [DM]/ha) were lower than the ad libitum regimen (1,784±69 and 1,333±33 kg DM/ha; p<0.05). The average herbage masses during lactation were 1,410±31 kg DM/ha. Nutritional regimen had no effect on ewe live weight, BCS and back fat depth or on lamb live weight, indices of colostrum uptake, maximal heat production, total litter weight weaned or survival to weaning (p>0.05). The difference in ewe BCSs and back fats observed among body condition groups was maintained throughout pregnancy (p<0.05). At weaning, ewes from the BCS2.0 group had lower BCS and live weight (2.4±0.2, 74.3±2.6 kg) than both the BCS2.5 (2.6±0.2, 78.6±2.4 kg) and BCS3.0 ewes (2.7±0.2, 79.0±2.6 kg; p<0.05), which did not differ (p>0.05). Ewe BCS group had no effect on lamb live weight at birth or weaning or on maximal heat production (p>0.05). Serum gamma glutamyl transferase concentrations of lambs born to BCS3.0 ewes were higher within 36 hours of birth than lambs born to BCS2.0 ewes and BCS2.5 ewes (51.8±1.9 vs 46.5±1.9 and 45.6±1.9 IU/mL, respectively [p<0.05]). There was, however, no effect of ewe body condition on lamb plasma glucose concentration (p>0.05). Lamb survival was the only lamb parameter that showed an interaction between ewe nutritional regimen and ewe BCS whereby survival of lambs born to BCS2.5 and BCS3.0 ewes differed but only within the Control nutritional regimen ewes (p<0.05). These results indicate farmers can provide twin-bearing ewes with pre- and post-grazing ryegrass-white clover herbage covers of approximately 1,100 and 800 kg DM/ha in late pregnancy, provided that herbage covers are 1400 in lactation, without affecting lamb performance to weaning. The present results also indicate that under these grazing conditions, there is little difference in ewe performance within the BCS range of 2.0 to 3.0 and therefore they do not need to be managed separately.

This study's hypothesis was that the nutrient composition in follicular fluid (FF) of ovarian follicles in early lactating postpartum cows may influence reagent transfer from cumulus cells (CC) to the oocyte. To test this, concentrations of amino acids (AA), cholesterol, glucose, and nonesterified fatty acids were measured in FF from the largest antral follicles at Days 21 and 46 postpartum during which time, most animals were expected to have resumed ovulatory activity. From the range of concentrations measured, two media compositions (Lac and Half-Lac) were prepared to compare with medium 199 (M199). The AA and cholesterol concentrations in FF were on average, approximately 35% and greater than 1000% higher than in M199, respectively. The nonesterified fatty acids, but not glucose, concentrations also exceeded those in M199. The transfer of fluorescent dye from CC to oocytes in bovine cumulus-oocyte complexes incubated with and without phosphodiesterase inhibitors (dipyridamole and milrinone) and/or forskolin was assessed. Maximum dye accumulation in oocytes incubated in M199 occurred after 4 hours and was further increased (P < 0.001) by dipyridamole. The addition of dipyridamole to Lac, but not Half-Lac, media also increased dye accumulation. There were effects of media (P < 0.001), cholesterol (P < 0.001), and forskolin (P < 0.05) on dye accumulation but no effects of stearic or palmitic acid in either Lac or Half-Lac media. The addition of oleic acid in Half-Lac (P < 0.01), but not Lac, media inhibited dye accumulation. These results support the hypothesis that reagent transfer from CC to oocytes is compromised when the AA composition in FF is low, as sometimes occurs during early lactation., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The focus of this study was to investigate the effect of subclinical endometritis (scEndo) on ovarian follicular steroid concentrations in early postpartum pasture-fed dairy cows. Mixed-age lactating dairy cows (n = 169) were examined to ascertain uterine health status on d 21 postpartum (±3 d). From this herd, a cohort of scEndo and uninfected cows (n = 47) were selected using uterine cytology to determine scEndo. To ensure cows with scEndo were selected for the study, a conservative threshold [>18% polymorphonuclear (PMN) cells among uterine nucleated cells] was chosen as a selection threshold. Ovarian follicular dynamics were assessed by ultrasonography on d 21, 42, and 63 postpartum. On the latter 2 d, all follicles >4 mm in diameter were ablated, and 4 d later, the largest (F1) and second largest (F2) follicles were measured and their follicular fluid aspirated. Hematological variables and plasma metabolites were measured also on these days to further characterize scEndo cows. On d 21, the prevalence of scEndo was approximately 9% in this herd; by d 42 infections had self-resolved in the majority (81%) of those cows classified as having scEndo on d 21. The scEndo cows had a delayed return to cyclicity; however, no effect was evident on ovarian follicle size or growth rate. Weeks after scEndo had self-resolved and cyclicity was restored, decreased (P = 0.07) testosterone and increased (P = 0.07) cortisol concentrations were evident in F1 follicles of scEndo compared with uninfected cows. Progesterone concentrations of F1 increased (P < 0.05) in 11- to 16-mm diameter follicles of scEndo cows, whereas estradiol, androstendione, and dehydroepiandrosterone concentrations were decreased (P < 0.05) in F1 8- to 10-mm diameter follicles of scEndo cows. These 3 steroids also differed (P < 0.05) between F1 follicle size categories of scEndo but not uninfected cows. On d 21, mean plasma albumin concentration was decreased (P = 0.02) in scEndo cows. In summary, early postpartum scEndo had surprisingly long-term influences on the steroid concentrations of ovarian follicles long after infections had self-resolved. This is likely to affect oocyte quality and may partially explain the reduced conception rates and longer interval between calving and conception that are often associated with scEndo, although more detailed investigations are required to substantiate this theory.

The objective of this study was to determine whether the physiological response to an intravenous glucose challenge would be affected by genetic strain or concentrate supplementation in grazing Holstein-Friesian cows in early lactation. North American (NA; n = 30) or New Zealand (NZ; n = 30) cows were randomly allocated to 1 of 3 feeding treatments. All cows were offered a generous pasture allowance, and 4 of the 6 groups received either 3 or 6 kg of dry matter (DM)/cow per day of concentrates. During wk 5 of lactation, all cows underwent an intravenous glucose challenge. Cows of NA origin produced more milk than NZ cows, but there was no significant strain effect on milk fat or protein yield. Milk yield and the yield of individual components increased with increasing level of concentrate eaten, but there were no significant strain x diet interactions. During wk 1 to 6, mean body weight and body condition score decreased in all treatments. Average body weight was greater in NA cows, but body condition score was greater for NZ cows. There was no strain or diet effect on the length of the postpartum anovulatory interval, with cows ovulating before 40 d postpartum on average. Glucose fractional turnover rate was greater in NZ cows compared with those of NA origin and in all cows receiving 6 kg of DM concentrates, indicating a less severe insulin resistance in those treatments. Consistent with this, the time taken to dispose of half the peak glucose concentration was less when 6 kg of DM concentrate was fed, and tended to be less in NZ than in NA cows. There was no effect of genetic strain on glucose area under the curve (AUC) at 60 or 120 min, but AUC at both time points was less in cows receiving 6 kg of DM concentrates per day. Neither genetic strain nor nutrition affected basal or peak insulin concentrations, insulin increment, or insulin AUC, and there were no strain x diet interactions for any of the glucose challenge response variables measured. In conclusion, differences in milk production between NA and NZ cows in early lactation can, at least in part, be explained by the greater degree of insulin resistance in the NA cows, and this insulin resistance can be overcome by supplementing grazing cows with 6 kg of DM concentrates.

Permeability studies of water through the skin and flesh of d'Agen plums have been carried out by radiotracer and PGSE NMR techniques as a function of moisture content. The results have shown that the diffusion coefficient of water through the skin layer increases as the fruit is dried at 70 degrees C or above. By contrast, the water diffusion through the fruit becomes more hindered as moisture is lost and structural collapse of the cell layers takes place. Values for diffusion coefficients of water at 21 degrees C through the fruit of 1 x 10(-)(9) m(2) s(-)(1) for fresh plums and 2.0 x 10(-)(10) m(2) s(-)(1) for fruit dried to 50% moisture content (wet basis) were found. Structural studies using scanning electron microscopy techniques were also performed. These showed that drying induces marked changes to the waxy skin layer of the fruit as well as the fruit flesh. These results are discussed in terms of the important role that the plum skin has in modulating the moisture loss process during dehydration, particularly at early stages of drying.

The principal advantage of the n.m.r. imaging method lies in the specific contrasts which are available. In this work we describe the use of velocity and diffusion contrast methods in biophysical applications and at microscopic spatial resolution. In the first example, involving water-protein interactions, the relationship between water self-diffusion and water concentration, as measured using pulsed gradient spin echo n.m.r., is shown. It is demonstrated that this relationship can be used to provide a water concentration image. The result is compared with the conventional proton density and transverse relaxation maps. The next example concerns the use of dynamic n.m.r. microscopy to obtain water diffusion and velocity maps for wheat grain in vivo. Finally we suggest how the method may be used in the study of polymer-water interactions in an unusual adjunct to conventional polymer self-diffusion studies.