Evaluation of an inexpensive needle test for the diagnosis of phosphorus deficiency and management of phosphorus supplementation for cattle: A multiple case study

Abstract

The needle test (NT) is a point-of-care test developed in Brazil to evaluate the Phosphorus (P) status in cattle. Based on bone resistance, the NT is a very inexpensive method which allows the diagnosis of any degree of P deficiency in a fast and simple way in vivo and directly on farm. The NT measures three levels of resistance in the transverse process (TP) of the lumbar vertebrae: a) TP that are impenetrable and result in warping of the needle (P healthy animals); b) TP offering some resistance to the penetration (animals with subclinical P deficiency); and c) TP which has minimal resistance to penetration (clinical P deficiency). This manuscript presents results from a series of case studies to evaluate the hypothesis that the NT could be used to assess P status in cattle and assesses the usefulness of results to support decision making on mineral supplementation strategies for grazing cattle. The NT was able to detect the changes in the resistance patterns of the TP, as there was reduction or elevation of P levels in the mineral mixtures. The NT was useful to assist in decision-making for adoption of mineral supplementation strategies better suited for each farm, helping farmers to save money and avoid unnecessary waste of P.

Physicochemical Evaluations of Diets, Rumen Fluid, Blood and Faeces of Beef Cattle under Two Different Feedlot Systems

“…Such case studies should be conducted to investigate complex environments, held in natural contexts and applied to contemporary matters. This approach is ideal for applications in field-oriented studies [ 13 ]. It is important to emphasise that case studies do not have randomization nor experimental control; therefore, hypothesis tests were not conducted for any variables in this paper.…”

Clinical parameters and calf liveweight of Nellore breeders supplemented or not with phosphorus, during pregnancy and lactation - a case study

“…Figure 1 shows the scheme used in the experimental phase E 1 . During E 1, about 10% of breeders were subjected to the needle test (NT), according to Malafaia et al (2018). The NT was performed when heifers were pregnancy-tested, then approximately 7 to 8 months of gestation and again 30 to 90 days after calving.…”

“…The NT was performed when heifers were pregnancy-tested, then approximately 7 to 8 months of gestation and again 30 to 90 days after calving. Similarly, three sequences of rib biopsies were also performed, according to Malafaia et al (2017), in four different heifers from G 40 and G 0 ; on the pregnancy-test day, the second between the 7 th and 8 th month of pregnancy and the final biopsy, between 30 and 90 days postpartum. After performing the biopsies, the animals were evaluated daily for clinical status, expression of pain signals (Fitzpatrick et al, 2006) and wound healing; after 14 days, after assuring that no animals had problems to heal, the sutures were removed.…”

“…Case studies should be conducted to investigate complex environments, held in natural contexts, and applied to contemporary matters, trying always that possible to be combined with other scientific approaches, such as the experimental method utilized in the current paper. This approach called meta-method is ideal for applications in field-oriented studies (Malafaia et al, 2018). Since case study does not have true replications nor casualization, hypothesis tests were not conducted for any variables in this paper.…”

“…Phosphorus is a metabolically essential mineral, and its deficiency may cause economic losses to cattle producers if animal performance is impaired. Nonetheless, Malafaia et al (2014); Malafaia (2020) highlight that there is a broadly spread misconception that this mineral should always be supplemented to cattle, even without a clinical-nutritional diagnosis of its deficiency in the herd. This simplistic view can result in an excessive intake of P in grazing herds, and lead to economic losses because no increments in cattle productivity are expected (Malafaia, 2020).…”