Biochemical profile of heifers with spontaneous humeral fractures suggest that protein-energy malnutrition could be an important factor in the pathology of this disease

Abstract

Case history: 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. Clinical findings: 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. Clinical relevance: 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.

An Assessment of the Epidemiology and Herd-Level Impact of the Fractured Humerus Epidemic in New Zealand Dairy Cattle, 2007–2015: Results from Four Studies

“…Since then, this trend has continued, and as of the 2021-2022 season, crossbred cows are now 59.2% of the population of dairy cows in New Zealand [35]. The national case series study suggested that fractures were more common in crossbred dairy cows, and although this was not supported by the practice-based survey, a recent paper has identified that farms where crossbred cattle are the main dairy breed are 9.7 times more likely to have humeral fractures than farms with other dairy breeds [36]. Unfortunately, the breed of affected cattle was not asked about in the national telephone survey, so this did not support or contradict the findings of the national case series.…”

“…Furthermore, the peak occurrence of humeral fractures in dairy cows appears to coincide with the resumption of cyclicity post-calving, with the increased physical activity due to oestrus behavior likely contributing to fracture occurrence. Recent studies on humeral fractures in New Zealand have reported that the condition is associated with periods of inadequate feed quality, leading to decreased bone formation and increased abnormal bone resorption that severely affects bone quality and strength [9][10][11]37,38]. Some support for this hypothesis is provided by a study in yearling zebu steers where an experimental dietary protein deficiency applied over 100 days resulted in evidence of mild rib osteoporosis, indicating an association with phosphorus and calcium and decreased absorption [39].…”

Atraumatic Fractures in Multi-Morbid Older Adults: A Series of Five Cases and Review of Literature

“…According to an animal pathology textbook, “most cases of osteoporosis in animals, especially farm animals, are nutritional in origin and may be caused by a deficiency of a specific nutrient, such as calcium, phosphorus, or copper, starvation, restricted and/or imbalanced intake.” It also highlights multiple mechanisms of malnutrition-induced MBDs [ 44 ]. Nutritional animal ATF outbreaks were reported in cows, associated with PEM, calcium mobilization for lactation, and copper deficiency [ 45 - 47 ]. Collagen content was significantly higher in the humeri of cows without fractures, while total collagen crosslink content was significantly higher in the humerus of cows with spontaneous fractures, indicating that PEM might be more important than copper deficiency [ 48 ].…”

Novel Assessment of Collagen and Its Crosslink Content in the Humerus from Primiparous Dairy Cows with Spontaneous Humeral Fractures Due to Osteoporosis from New Zealand

“…In undernourished cattle, there is a significant reduction in serum albumin and creatinine concentration compared to adequately nourished animals [ 35 ]. We have previously shown that 69% of affected cows have low creatinine concentrations which was linked to low muscle mass and protein/calorie undernutrition [ 36 ]. Likely, undernutrition and/or low muscle mass and/or low body condition score may explain the lower total collagen content in bone from affected cows in this study.…”