Clinical and pathological findings of phosphorus (P) deficiency in cattle in Tocantins and its economic impact - case report

[Achados clínicos e patológicos da deficiência de fósforo (P) em bovinos no Tocantins e seu impacto econômico - relato de caso]

ABSTRACT

The objective of this study is to describe the occurrence of natural cases of phosphorus (P) deficiency in ruminants in the state of Tocantins, Brazil, and its epidemiological, clinical, and economic relevance. Three cases were monitored, in which physical examination, complete blood count, serum biochemistry, evaluation of bone phosphorus concentration, specific gravity, and ash percentage were performed. The animals presented low body condition scores and osteophagia. In Case I, one animal exhibited neurological signs, including flaccid paralysis and tail paralysis, lingual atony, and a decreased panniculus reflex. In Case III, some animals showed grade II lameness. All other clinical parameters were within normal limits. Hematological and biochemical parameters were also within the reference range for the species. However, bone phosphorus concentration, specific gravity, and ash percentage were all below reference values. The estimated annual productive losses due to inadequate phosphorus supplementation were $84,760.01 for Case I, $5,398.35 for Case II, and $5,364.81 for Case III. This is the first descriptive report of phosphorus deficiency in cattle in the state of Tocantins.

Keywords:
botulism; cattle; mineral deficiency; osteophagia

RESUMO

O objetivo deste estudo é descrever a ocorrência de casos naturais de deficiência de fósforo (P) em ruminantes no estado do Tocantins, Brasil, e sua relevância epidemiológica, clínica e econômica. Três casos foram monitorados, nos quais foram realizados exame físico, hemograma completo, bioquímica sérica, avaliação da concentração de fósforo ósseo, gravidade específica e porcentagem de cinzas. Os animais apresentaram baixo escore de condição corporal e osteofagia. No caso I, um animal apresentou sinais neurológicos, incluindo paralisia flácida e paralisia da cauda, atonia lingual e diminuição do reflexo do panículo. No caso III, alguns animais apresentaram claudicação grau II. Todos os demais parâmetros clínicos estavam dentro dos limites normais. Os parâmetros hematológicos e bioquímicos também estavam dentro dos valores de referência para a espécie. No entanto, a concentração de fósforo ósseo, a gravidade específica e a porcentagem de cinzas estavam todas abaixo dos valores de referência. As perdas produtivas anuais estimadas devido à suplementação inadequada de fósforo foram de US$ 84.760,01 no caso I, US$ 5.398,35 no caso II e US$ 5.364,81 no caso III. Este é o primeiro relato descritivo de deficiência de fósforo em bovinos no estado do Tocantins.

Palavras-chave:
botulismo; bovinos; deficiência mineral; osteofagia

INTRODUCTION

Cattle farming represents a significant portion of Brazil’s GDP, with the production of 2.38 million tons of beef carcasses and 6.47 billion liters of milk in just the first quarter of 2025 (Pesquisa…, 2025). Mineral deficiencies compromise livestock efficiency by reducing weight gain and productivity, decreasing reproductive rates, lowering immunity, increasing disease susceptibility, and reducing feed conversion efficiency (Malafaia et al., 2023).

Phosphorus (P) is the second most deficient mineral globally and the most economically significant (Suttle, 2010). Deficient animals may exhibit hyporexia, cachexia, postpartum hemoglobinuria, reproductive disorders, rickets, osteomalacia, frequent fractures, and osteophagia, which can lead to choking and/or botulism (Nicodemo et al., 2000; Malafaia et al., 2023).

Diagnosis is based on history, anamnesis, clinical and pathological findings (Tokarnia et al., 2010; Suttle, 2010), measurement of phosphorus levels in blood and bone via laboratory testing, or therapeutic diagnosis through phosphorus supplementation (Nicodemo et al., 2000; Tokarnia et al., 2010).

Despite previous reports of phosphorus (P) deficiency in ruminants in Brazil (Malafaia et al., 2023; Nicodemo et al., 2000), there have been no records of this deficiency in the state of Tocantins, one of the country’s leading cattle-producing and exporting regions (Brasil, 2024).

The objective of this study is to describe the occurrence of natural cases of phosphorus (P) deficiency in ruminants in the state of Tocantins, Brazil, and its epidemiological, clinical, and economic relevance.

ETHICAL ASPECTS

This research was not submitted to the Ethics Committee on Animal Use.

CASUISTRY

Cases of phosphorus (P) deficiency were reported on three different farms. All followed an extensive grazing system and were in the municipality of Araguaína, state of Tocantins, northern Brazil (Latitude: 7° 11' 31'' South, Longitude: 48° 12' 28'' West).

Case I occurred in August (dry season) on a farm with a herd of 500 crossbred cattle (males and females), aged 12 to 60 months, raised for both milk and meat production. The main complaint was progressive weight loss among the animals, with six deaths reported. The pastures were predominantly Panicum maximum, but highly degraded due to the dry season. Water sources included rivers and ponds. The animals received commercial mineral salt offered in uncovered troughs. The owner reported that the problem had been ongoing for several months and noted bone-chewing behavior among the animals. The herd showed weight loss, general apathy, and, by the time of the visit, six animals had already died.

Case II occurred in December (rainy season) on a farm with 37 crossbred cattle (males and females), aged 8 to 60 months, used for dairy production. Pastures were composed of Panicum maximum, with good green forage availability per animal. Water sources included ponds and drinkers. The animals were given commercial mineral supplements (Table 1), mixed in a 1:1 ratio with plain salt and provided in uncovered troughs. The farmer reported bone-chewing behavior in some animals, as well as progressive weight loss in the herd.

Table 1
Mineral composition (g/kg or mg/kg) of the commercial supplement used in Cases I and II.

Mineral	Ca¹	P¹	Na¹	S¹	Co²	Cu²	Cr²	Fe²	I²	Mg²	Se²	Mo²	Zn²	F²
Case I	120	90	147	18	40	590	20	1800	80	1300	15	300	3800	870
Case II	110	90	150	18	30	500	20	1800	80	1300	15	300	3800	870

• ¹ Mineral supplemented in g/kg; ² Mineral supplemented in mg/kg.

Case III occurred in July (dry season), in a land settlement project (Projeto de Assentamento - PA), with 28 crossbred beef cattle (males and females), aged 12 to 60 months. Pastures consisted of native vegetation and some areas with Urochloa decumbens. No mineral supplementation was provided. The farmer reported cachexia, poor weight gain, severe post-partum deterioration, weakness, and osteophagia as the main problems.

In all three cases, physical examination was performed following Feitosa (2008), revealing low body condition score (BCS) and osteophagia (Fig. 1). In Case I, one animal exhibited neurological signs such as flaccid paralysis, tail paralysis, lingual atony, and a reduced panniculus reflex. In Case III, some animals presented grade II lameness, and osteophagia was confirmed through bone fragment offering (Fig. 1C). Other clinical parameters were within normal limits.

Figure 1
Cattle displaying osteophagia due to phosphorus deficiency in Araguaína, Tocantins.

Blood samples were collected via jugular venipuncture for hematology and biochemistry analyses, according to Thrall et al. (2015). All parameters were within the normal range for the species.

The animal with neurological signs in Case I died during the visit and was necropsied following Santos and Alessi (2016). The only significant finding was extreme cachexia. Fragments of major organs were collected, fixed in 20% formalin, processed for histological analysis, stained with hematoxylin and eosin (H&E), and examined under light microscopy. No significant histopathological changes were observed.

A rib bone fragment (12th rib) was collected in Case I for analysis of bone phosphorus concentration, specific gravity, and ash percentage. In Cases II and III, bone biopsies were performed following Malafaia et al. (2017) for the same evaluations. All measured parameters were below reference values (Table 2).

Table 2
Average values of the evaluated parameters

Parameter	Case I	Case II	Case III	Reference Value
Bone P concentration (%)	10.5	9.99	9.15	>11.5¹
Specific density (g/mL)	1.65	1.57	1.51	1.69²
Ash percentage (%)	64.0	61.53	60.62	≥66.8³

• ¹Tokarnia et al. (2010). ² Valdes et al. (1988). ³ Little (1972)

DISCUSSION

This is the first descriptive report of cases of phosphorus (P) deficiency in cattle in the state of Tocantins. To date, no references or reports of phosphorus deficiency in cattle in this state have been found.

The three properties in this report have crossbred herds raised in extensive grazing systems. It is known that in extensive systems, soils tend to be deficient, exposing animals to mineralization problems, especially phosphorus deficiency (Tokarnia et al., 2010). Furthermore, in Brazil, most forage species used have low nutritional requirements to facilitate adaptation to local conditions, given that Brazilian soils are generally mineral-deficient. As a result, these species have low concentrations of crude protein (CP), total carbohydrates (TC), and essential minerals (Tokarnia et al., 2010). Consequently, nutritional disorders are common in herds that depend on these forages as their main food source.

Mineral deficiencies must be corrected with effective supplementation to prevent the manifestation of disorders or diseases associated with mineral deficits (Suttle, 2010; Tokarnia et al., 2010). The mineral mix must meet the species' requirements, considering its production level and the nutritional gap of the consumed forage, as well as the region and time of year (Suttle, 2010; Tokarnia et al., 2010). It should also be considered that degrees of deficiency vary by region, and commercial mineral supplements may not be tailored to all realities, often supplying minerals in excess or insufficient amounts (Malafaia et al., 2014).

Additional factors aggravating mineral deficiencies commonly observed on farms include the use of uncovered troughs, where minerals are lost due to rain (Malafaia et al., 2014), as seen in Cases I and II; dilution of products (Malafaia et al., 2014), as in Case II; or even worse, the complete absence of supplementation, as seen in Case III-an issue found in approximately one-third of Brazilian farms. At a minimum, NaCl should be supplemented for cattle in all regions of the world (Malafaia et al., 2014).

In the cases evaluated, clinical signs such as reduced feed intake, weight loss, general apathy, neurological alterations, flaccid paralysis, low milk production, and altered appetite (osteophagia) were consistent with other reports in the literature (Malafaia et al., 2023; Barbosa et al., 2021).

Osteophagia was reported in all cases and is considered by many authors the main clinical sign of phosphorus deficiency (Suttle, 2010; Tokarnia et al., 2010). Neuromuscular alterations such as flaccid paralysis and tail paralysis, tongue atony, and reduced panniculus reflex have been described in association with botulism (Nascimento et al., 2024).

Except for extreme cachexia, no noteworthy alterations were found in the necropsies performed in Case I, consistent with findings by Martins (2014), who reported no macroscopic lesions. However, Barbosa et al. (2021) described changes such as bone fractures, widened medullary cavities, emaciated carcasses with dull coats, enlarged growth plates, angular deformities, and shortened long bones. Structural changes may depend on the stage of deficiency, and morphological and histological changes may or may not be sufficiently pronounced to be detected at necropsy or through histological analysis (Tokarnia et al., 2010).

The hematological parameters of the evaluated animals showed no significant alterations, consistent with Tokarnia et al. (2012), who stated that tissue changes are more evident and reliable indicators of nutritional status. Blood parameters fluctuate due to endocrine metabolic control and recent nutrient intake, potentially masking nutritional deficiencies (Thrall et al., 2015).

In the present study, all reported cases showed bone phosphorus concentrations below the normal value of >11.5% for cattle, indicating phosphorus deficiency according to Suttle (2010) and Tokarnia et al. (2010). Additionally, lower values for bone specific density (g/mL) and ash content (%) support the possibility of bone resorption. Bone biopsy is frequently used to estimate changes in mineral reserves in cattle, as it provides detailed and accurate information about bone phosphorus concentration and allows direct observation of pathological alterations associated with deficiency. However, the procedure is invasive and carries risks of complications, such as infections, and biopsy samples may not reflect the overall mineral status of the body (Malafaia et al., 2017).

It is crucial to diagnose phosphorus deficiency in cattle, as it leads to health problems such as rickets, stunted growth, bone fractures, and decreased productivity, as well as economic losses (Nicodemo et al., 2000). In fact, phosphorus deficiency is the most common mineral deficiency in Brazilian ruminants, affecting cattle, sheep, and goats (Malafaia et al., 2023).

Among variable production costs, mineral supplementation ranks as the second or third highest (Magnoli Costa, 2004). Inadequate supplementation leads to direct losses such as reduced weight gain, decreased milk production, reproductive failure, and mortality, as well as indirect losses like increased disease susceptibility, feed inefficiency, veterinary costs, diagnostic tests, medications, and issues such as fractures and botulism (Malafaia et al., 2004).

In this report, even with mineral supplementation (Cases I and II), animals exhibited problems due to mineral deficiency. The literature reports that average weight gain was up to 26.4% lower in cattle receiving commercial supplementation compared to selective supplementation, while the commercial supplement cost was up to 309% higher (Malafaia et al., 2004). Another study showed that supplementing dairy cows with an appropriate mineral mix increased milk production by an average of 1.45 liters per day (Islam et al., 2023). Based on these estimates, the annual productive loss due to inadequate supplementation was estimated at $84,760.01 for Case I, $5,398.35 for Case II, and $5,364.81 for Case III (Table 3).

Table 3
Estimated productive loss due to inadequate mineral supplementation in the three reported cases.

	Case I		Case II	Case III
Type of production	Beef	Dairy	Dairy	Beef
Herd	250	250	37	28
Lactating or fattening animals	200	200	30	22
Daily losses	42.24Kg	290 L	43.5 L	4.64 L
Bonus loss per day ($)	133.62	98.60	14.79	14.70
Annual loss ($)	48,771.01	35,989.00	5,398.35	5,364.81

• *Calculations were based on 80% of the herd being in lactation or finishing; a 26.4% increase in weight gain with proper supplementation (Malafaia et al., 2004); a 1.45-liter increase in milk production per day with proper supplementation (Islam et al., 2023); $0.34 as the average price per liter of milk paid to producers ((Pesquisa…, 2025); and $47.45 as the price per arroba of beef (Indicador…, 2024).*

These losses do not include veterinary expenses, tests and medications, reduced pregnancy rates, treatment of secondary diseases, and other associated factors. If we consider the 6 deaths in Case I, we must add a loss of $6,833.26 from 144 arrobas lost by the producer. It is known that the production chain is complex with many variables, making it impossible to calculate the full extent of losses caused by inadequate supplementation, but these values accumulate and become exorbitant when the issue is ignored.

Therefore, proper mineral supplementation is essential to provide the necessary phosphorus levels for animals, given the importance of this mineral in bone formation, metabolic and energy processes.

CONCLUSION

This study reports the first documented occurrence of phosphorus deficiency in cattle in the state of Tocantins, emphasizing the importance of appropriate mineral supplementation. Cases of nutritional deficits and increased susceptibility to botulism were observed in herds grazing on degraded pastures under extensive systems with improper mineral supplementation. The clinical signs and low levels of bone phosphorus and density indicate an urgent need for correction of these deficiencies to ensure the health and productivity of the herd.

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• DATA AVAILABILITY STATEMENT
  The research data are available within the article itself.

Edited by

• Editor-chefe:
  Marcelo Resende de Souza

• Editor-científico:
  Antônio de Pinho Marques Jr.

Data availability

The research data are available within the article itself.

Publication Dates

• Publication in this collection
  06 July 2026
• Date of issue
  May-Jun 2026

History

• Received
  19 July 2025
• Accepted
  22 Dec 2025