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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. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine if diets differing in crude protein (CP) to metabolizable energy (ME) ratio (CP:ME) pre-weaning altered peripheral quantitative computed tomography (pQCT) measures of bone mass and strength in lambs. The left hind leg of lambs were available at the completion of a trial designed to examine the effect that altering the CP:ME ratio in milk replacer had on growth and body composition of pre-weaned lambs reared artificially. Treatments consisted of either normal commercial milk replacer (CMR, n = 10) containing 240 g/kg CP and 21.89 MJ/kg ME, high protein milk replacer (HPM, n = 9) containing CMR with additional milk protein concentrate to reach 478.7 g/kg CP and 19.15 MJ/kg ME or a mix of normal milk replacer and milk protein concentrate adjusted twice-weekly to match optimal CP:ME requirements (MB, n = 8) based on maintenance plus 300 g/d liveweight gain. At 22 kg live weight, lambs were euthanized and the tibia including the surrounding muscle was collected and scanned using pQCT at the mid-diaphysis. Lambs on the HPM and MB diets had a greater average daily gain (p < 0.01). There were limited differences in bone morphology and muscle mass, though notably the higher protein diets (MB and HPM) were associated with greater cortical thickness (p < 0.05) and, therefore, potentially greater peak bone mass at maturity This finding demonstrates that pre-weaning diets, and the protein content in particular, may influence the developmental potential of long bones and attainment of peak bone mass at maturity. [ABSTRACT FROM AUTHOR]

Bone morphology in the mid-diaphysis of the metacarpus in cattle and the effect of puberty and age has been well described. However, there is limited information on how age and not attaining puberty affects bone morphology in the epiphysis of the metacarpus. The metacarpus is comprised of the third and fourth metacarpal bones fused together to create a medial and lateral epiphysis. When a cow is in stance phase there is greater pressure on the medial claw; however, the effect of this difference in loading on bone has not been described. Therefore, the aim of this experiment was to describe bone morphology in the medial and lateral epiphysis of the metacarpus at the age of puberty in steers. The metacarpus was collected from beef cross dairy steers at approximately one and two years of age. The distal epiphysis of the metacarpus was scanned using peripheral quantitative computed tomography (pQCT). Measures were corrected for body weight and demonstrated a lack of bone growth cessation at one year of age. The lack of difference in bone morphology in the medial and lateral condyles of the distal metacarpus reflects the even loading distribution observed in the forelimb of cattle. [ABSTRACT FROM AUTHOR]

Selection pressure for greater milk solid production, calving ease and early puberty attainment has resulted in the alteration of the growth trajectory of New Zealand dairy heifers. Although previous data have looked at stature growth in terms of height and girth, changes in the growth trajectory as a result of seasonal growth has not been examined. In addition, the relative contributions of the appendicular skeleton and thorax in relation to height have not been considered in previous studies. Therefore, the aim of this study was to examine how the proportional contributions of stature change with increases in live weight in Holstein–Friesian, Jersey and Holstein–Friesian–Jersey crossbred heifers from birth to 23 months of age (just prior to calving). Comparisons of height, length, girth and distal and proximal forelimb length (stature) revealed that at the same live weight, measures of girth, length and height did not differ between breeds (p < 0.05). As live weight increases, the relative contribution of the distal limb to increasing height decreases, which is consistent with the cessation of physeal growth occurring earlier in the bones of the distal limb than in the proximal limb. By understanding the timing of proximal and distal growth in dairy heifers, the effect of seasonal growth on longitudinal bone growth can be identified. [ABSTRACT FROM AUTHOR]

Growth rates associated with different artificial rearing systems have been thoroughly examined in many species. However, the effect of different rearing systems on bone morphology has not been described. The objective of this study was to examine differences in the bone mass and the relationship of peripheral quantitative computed tomography (pQCT) measures of bone with muscle area of ewe-reared lambs and artificially reared lambs. Lambs were opportunistically collected from a concurrent trial examining changes in ewe mammary glands during lactation. Thirteen lambs were artificially reared while the remaining nine were left on their dam. Measures of stature were taken throughout the six-week trial period. At approximately six weeks of age, the lambs were euthanized and the tibia was collected and scanned using peripheral quantitative computed tomography. Artificially reared lambs had reduced live weight gain and an altered pattern of stature growth. There was no effect of treatment on bone morphology (p > 0.05), but ewe reared lambs had a greater cortical bone content to muscle area ratio than artificially reared lambs (0.06 vs. 0.15, respectively). Differences in growth between ewe reared lambs and artificially reared lambs emphasizes the importance of adequate preweaning nutrition for livestock production systems that routinely use artificial rearing systems. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare conformation, age at puberty and subsequent milk production of Holstein–Friesian–Jersey crossbred heifers grown in a linear trajectory (Target; n = 55) between 6- and 15-month target liveweights (LWT), with heifers grown in a seasonal manner (Seasonal; n = 55) of slow over first winter and fast over spring. Heifers that grew to Target attained puberty 38 days earlier than heifers that grew in a seasonal manner; however, no difference between treatments in the date of first calving occurred. Heifers in the seasonal treatment were 1 cm (P =.032) taller than those in the target treatment, but similar in girth and length. There was no effect of treatment on first lactation milk production. These results suggest that provided heifers reached their pre-mating target LWT, the growth trajectory between target LWT at 6 and 15 months of age did not negatively impact frame size or first lactation milk production. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare breed proportions, genetic merit, milk production and survival of carryover and non-carryover dairy cows in New Zealand. Calving interval was used as a tool to identify cows that had an extended non-lactating period and then returned to a milking herd. A greater proportion of Holstein-Friesian was observed in the breed composition of the carryover cows. Estimated breeding values (EBVs) for milk traits were greater, but the EBVs for fertility were lower for carryover cows, than those for non-carryover cows. Carryover cow genetic merit values were greater than those for non-carryover cows in the year prior to their carryover period. Carryover cow milk production was significantly greater than that of non-carryover cows. The average survival days and probability of survival for second-lactation carryover cows was lower than that for first-lactation and lactation-matched non-carryover cows. These results are important for culling decisions made by pastoral dairy farmers. [ABSTRACT FROM AUTHOR]

Liveweight targets in the New Zealand dairy industry aim to increase subsequent productionof heifers. The aim of this experiment was to determine the effect of the percentage of individual liveweight target achieved at 6, 9, 12 and 15 months of age, on heifers' reproductive performance and on milk production in first lactation, using retrospective analysis of a cohort of replacement heifers within a New Zealand dairy herd Heifers that reached liveweight targets at 12 and 15 months of age had longer lactations and produced more milksolids than heifers that were behind target. The increase in production from increasing percentage of liveweight target was greater for heifers that were further below their target live weight. This experiment supported the need to have heifers close to liveweight target at 12 and 15 months, but there were only limited advantages of greater percentage of liveweight target achieved at 6 and 9 months of age. [ABSTRACT FROM AUTHOR]

Fodder beet and kale are commonly used winter crops in New Zealand dairy and dairy support farm systems. Fodder beet (FB) is known to have lower crude protein, phosphorus and calcium content compared to kale. The intrauterine effects of feeding FB during late pregnancy on bone growth and development in calves requires attention. This study aimed to examine the intrauterine effects of a maternal diet of either kale or FB on measures of calf stature and bone morphology at birth. In winters 2019 and 2020, two herds of pregnant Friesian × Jersey cows were fed either kale (2019, 2020 n = 20) or FB (2019, 2020 n = 20) supplemented with pasture baleage. Calves born from these mobs were euthanised within ten days of birth and a forelimb and section of rib including the costochondral junction were harvested for peripheral quantitative computed tomography and histological analysis. Calves from the FB treatment had reduced bone density and strength compared to calves from the kale treatment (p < .05). The effect of a nutritional deficit on bone morphology at birth emphasises the importance of sufficient nutrition in pre-calving diets. Future research is required to examine the long-term impact of dam undernutrition on calf growth and production. [ABSTRACT FROM AUTHOR]

The objective of this study was to model the growth of dairy heifers to estimate the effects of breed and heterosis on live weight (LWT) and growth from three to 22 months of age. Data comprised of 1,653,214 LWT records obtained from 189,936 dairy heifers in 1547 herds. At all ages Holstein-Friesian (F) heifers were heavier than Holstein-Friesian-Jersey crossbred (F × J) which were heavier than Jersey (J) heifers. Heterosis effects for LWT were greatest at nine months of age (3.6%) and least at 22 months of age (2.0%). The growth pattern differed, as evidenced by the regression coefficients of the Legendre polynomial. Growth was non-linear and heterosis effects were different throughout the growth period. Friesian, J and F × J heifers exhibited different growth patterns. These differences in growth pattern should be considered when formulating target LWTs and growth rates for a pasture-based system. [ABSTRACT FROM AUTHOR]

To adjust for potential overestimations in the nitrogen excretion by horses within Overseer®, a revised stock unit system has been proposed (equineRSU). These equineRSU were generated and validated using a medium-sized equine farm as a model farm. The aim of this study was to test the application of the equineRSU and seasonal stock number adjustment on a more complex farming model. Livestock numbers and management data were captured prospectively for the base property (128.8 ha) of a large multi-property commercial breeding stud (3 support properties, 556 ha total area) between June 2022 and May 2023. The monthly on-farm metabolisable energy (ME) requirement and pasture demand were deterministically modelled with both a customised feed budget using livestock class and weight or using the equineRSU and monthly adjusted stock numbers. There were multiple complex movements of horses on and off the property in the different stock classes across the year, with stock management reflecting seasonal periods of high stocking density. There was good agreement (6% variance) between actual ME demand (complex feed budget) and estimated feed demand (simplistic equineRSU model) of 4,387,187 MJ vs 4,102,770 MJ. This suggests that the equineRSU could be used on complex equine farm systems within Overseer®. [ABSTRACT FROM AUTHOR]

Plantain ( Plantago lanceolata L.) contains bioactive compounds with antimicrobial activity that can potentially influence ruminal fermentation. This study aimed to identify the concentration of the bioactive compounds catalpol, aucubin, and acteoside in plantain cv. ‘Ceres Tonic’ through two consecutive growing seasons (2011–2012 and 2012–2013). Then the herbage with highest levels of bioactive compounds was used to evaluate their effect on rumen in vitro fermentation. Plantain cv. ‘Ceres Tonic’ had almost nil concentration of catalpol. Both aucubin and acteoside concentrations increased (P < 0.05) through the growing season. Aucubin increased from 1.78 to 3.80 mg/g DM in the first and from 0.44 to 6.87 mg/g DM in the second growing season; while, acteoside increased from 23.6 to 35.4 mg/g DM and from 0.5 to 41.7 mg/g DM, respectively. The in vitro experiment evaluated the effect of aucubin and acteoside on ammonia (NH 3 ), volatile fatty acids (VFA) and gas production (GP) parameters. Aucubin and acteoside were added to chicory ( Cichorium intybus L.) as negative and to plantain as positive controls. The treatments were (i) chicory (CH); (ii) chicory + 10 mg aucubin/g DM (C+au); (iii) chicory + 20 mg aucubin/g DM (C+2au); (iv) chicory + 40 mg acteoside/g DM (C+ac); (v) plantain naturally containing 7 mg/g DM of aucubin and 36 mg/g DM of acteoside (PL); (vi) plantain + extra 10 mg aucubin/g DM (P+au); and (vii) plantain + extra 36 mg acteoside/g DM (P+ac). Plantain with natural concentrations of bioactives produced 40% less NH 3 than chicory over 24 h. The exogenous addition of both bioactive compounds reduced net NH 3 production by CH and PL. The increase in potential GP from acteoside fermentation suggested its use as an energy source. Whereas, the addition of aucubin reduced the rate of GP at dose level, potentially due to its bactericide activity. Therefore, acteoside would have a greater positive effect than aucubin on ruminant animals. [ABSTRACT FROM AUTHOR]

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.)