PESQUISA VETERINÁRIA BRASILEIRA

Abstract in English:

Copper is an essential micromineral in animal feed; however, when consumed in excess, it can cause liver necrosis, hemolytic crisis, hemoglobinuric nephrosis and death in cattle. Although uncommon in this species, copper poisoning occurs as a result of exacerbated supplementation, deficiency of antagonist microminerals, or previous liver lesions. An outbreak of chronic copper poisoning is reported in semi-confined cattle after supplementation with 50 mg/Kg of dry matter copper. The cattle showed clinical signs characterized by anorexia, motor incoordination, loss of balance, jaundice, brownish or black urine, diarrhea and death, or were found dead, 10 to 302 days after consumption. Of the 35 cattle that died, 20 underwent necropsy, whose frequent findings were jaundice, enlarged liver with evident lobular pattern, black kidneys, and urinary bladder with brownish to blackish content. Microscopically, the liver showed vacuolar degeneration and/or zonal hepatocellular centrilobular or paracentral coagulative necrosis, in addition to cholestasis, mild periacinal fibrosis, apoptotic bodies, and mild to moderate mononuclear inflammation. Degeneration and necrosis of the tubular epithelium and intratubular hemoglobin cylinders were observed in the kidneys. Copper levels in the liver and kidneys ranged from 5,901.24 to 28,373.14 µmol/kg and from 303.72 to 14,021 µmol/kg, respectively. In conclusion, copper poisoning due to excessive nutritional supplementation is an important cause of jaundice, hemoglobinuria, and death in semi-confined cattle.

• Copper poisoning beef cattle Mato Grosso Brazil semi-confinement mineral supplementation cattle diseases trace elements jaundice

Abstract in Portuguese:

Cobre é um micromineral essencial, que quando em excesso induz necrose hepática, crise hemolítica, nefrose hemoglobínurica e morte em bovinos. As intoxicações, apesar de incomuns nessa espécie, ocorrem devido a suplementação exacerbada de cobre, pela deficiência de microminerais antagonistas ou secundária a lesão hepática prévia. Relata-se um surto de intoxicação crônica por cobre em bovinos semiconfinados após suplementação com 50mg/kg de cobre em matéria seca. Os bovinos manifestaram sinais clínicos caracterizados por anorexia, incoordenação motora, perda de equilíbrio, icterícia, urina acastanhada ou negra, diarreia e morte ou foram encontrados mortos, após 10 a 302 dias do início de consumo. De 35 bovinos que morreram 20 foram submetidos à necropsia sendo achada frequente icterícia, fígado aumentado e com padrão lobular evidente, rins pretos e bexiga urinária repleta de conteúdo acastanhado a enegrecida. Microscopicamente, no fígado havia degeneração vacuolar e ou necrose coagulativa hepatocelular zonal, centrolobular ou paracentral, além de degeneração vacuolar com corpúsculos de Councilman, colestase, fibrose periascinar leve, e inflamação de discreta a moderada. Nos rins havia degeneração e necrose do epitélio tubular assim como cilindros de hemoglobina intratubulares. Os níveis de cobre no fígado e rim foram de 5.901,24 a 28.373,14µmol/kg e 303,72 a 14.021µmol/kg respectivamente. A suplementação nutricional excessiva com cobre pode causar doença hemolítica com icterícia, hemoglobinúria e morte de bovinos mantidos em sistema de semiconfinamento.

• Intoxicação por cobre bovinos de corte Mato Grosso Brasil semiconfinamento suplementação mineral doenças de bovinos oligoelementos icterícia

Abstract in English:

Dietary chromium supplementation before, during, and after weaning was conducted to evaluate the hypothesis that chromium supplementation could reduce weaning-induced cortisol release in beef calves. We examined the effects of chromium supplementation in 150 crossbred calves (male and female) between five and six months of age. The calves were randomly divided by sex and breed into two equal homogeneous groups (n=75). One group was used as the control, and the other experimental group received supplementation with 0.9mg of chromium carbon-amino-phospho-chelate per 100kg BW. The chromium supplement was mixed with mineral salt for the consumption of 0.1% of BW, and the supplement was administered via creep feeding 60 days before and 60 days after forced weaning. Calves were weighed, and their blood and urine samples were obtained at four time-points: T0 (60 days before weaning), T1 (at weaning), T2 (48 hours after weaning), and T3 (60 days after weaning). Blood samples were used to determine chromium, cortisol, total protein, and albumin concentrations, and urine samples were used to determine urinary creatinine and chromium levels. Cumulative weight gain was higher in calves supplemented with chromium before weaning and during the experiment (P<0.05). In addition, weaning-related stress caused an increase in chromium excretion in the urine, and chromium supplementation reduced stress, which resulted in lower cortisol and total protein levels during weaning.

• Organic chromium supplementation beef calves weaning stress cattle performance stress mineral supplementation chromium

Abstract in Portuguese:

O estudo foi realizado para avaliar a hipótese de que a suplementação dietética com cromo antes, durante e após a desmama possa diminuir a concentração de cortisol causado por este processo em bezerros de corte. Para tal, foram utilizados 150 bezerros mestiços, machos e fêmeas, entre cinco e seis meses de idade. Os animais foram divididos randomicamente por sexo e grupo genético em dois grupos homogêneos (n=75), um mantido como controle e outro suplementado com 0,9mg de carboaminofosfoquelato de cromo/100 kg PV misturado a um sal proteinado para ser consumido na base de 0,1% do PV via creep feeding, no decorrer de 60 dias antes e 60 dias após à desmama forçada. Os animais foram pesados e foram coletadas amostras sanguíneas e urinárias no M0 (60 dias antes da desmama), M1 (desmama), M2 (48 horas após a desmama) e M3 (60 dias após à desmama) para determinação de cromo, cortisol, proteína total e albumina no sangue e da concentração urinária de creatinina e cromo. O ganho acumulado de peso foi superior nos bezerros suplementados com cromo antes da desmama e no decorrer de todo o experimento (P<0,05). A suplementação com cromo reduziu os teores de cortisol e de proteína total durante a desmama. O estresse da desmama provocou aumento da excreção de cromo pela urina.

• Suplementação cromo orgânico bezerros de corte estresse da desmama bovinos desempenho estresse suplementação mineral desmama

Abstract in English:

ABSTRACT.- Barbosa F.B., Bomjardim H.A., Helayel M.J.S.A., Faial K.C.F., Oliveira C.M.C., Malafaia P., Brito M.F. & Barbosa J.D. 2016. [Economic evaluation of three strategies of mineral supplementation for beef cattle in State of Pará, Brazil.] Avaliação econômica de três tipos de suplementação mineral para bovinos de corte no estado do Pará. Pesquisa Veterinária Brasileira 36(7):600-604. Instituto de Medicina Veterinária, Faculdade de Medicina Veterinária, Universidade Federal do Pará, Campus de Castanhal, Rodovia BR-316 Km 61, Castanhal, PA 68741-740, Brazil. E-mail: diomedes@ufpa.br Three alternatives of mineral supplementation of 18 to 20-month-old male Nelore cattle with 299.5 to 308.5 kg of body weight were used at a farm in northeast of Pará state, Brazil. To evaluate which mineral mixture resulted in better cost-benefit, three groups of 20 head were supplemented for six months, from March to August of 2012. Group 1 was supplemented with a selected mineral mixture (SMM) composed of 25kg NaCl, 50kg dicalcium phosphate, 190g copper sulphate, 60g cobalt sulphate, and 15g sodium selenite, having 133g Na, 123g P, 631mg Cu, 167mg Co, and 9mg Se per kg; this mixture was made based in previous clinical-nutritional examination of herd. Group 2 (control), supplemented only with NaCl; and group 3 received a commercial mineral mixture (CMM), routinely used in this farm, with 130g P, 220g Ca, 18g Mg, 36g S, 6000mg Zn, 1500mg Cu, 2000mg Mn, 200mg Co, 90mg I, and 36mg Se per kg. Concentrations of phosphorus, copper, zinc and iron were determined in liver and 12th ribs. The best cost-benefit alternative was the SMM; the forage alone did not contain enough Co to meet the requirements of the control group, but provided enough P, Cu, Zn and Se during the five months of the experiment.

• Mineral deficiencies deficiência mineral

Abstract in Portuguese:

RESUMO.- Barbosa F.B., Bomjardim H.A., Helayel M.J.S.A., Faial K.C.F., Oliveira C.M.C., Malafaia P., Brito M.F. & Barbosa J.D. 2016. [Economic evaluation of three strategies of mineral supplementation for beef cattle in State of Pará, Brazil.] Avaliação econômica de três tipos de suplementação mineral para bovinos de corte no estado do Pará. Pesquisa Veterinária Brasileira 36(7):600-604. Instituto de Medicina Veterinária, Faculdade de Medicina Veterinária, Universidade Federal do Pará, Campus de Castanhal, Rodovia BR-316 Km 61, Castanhal, PA 68741-740, Brazil. E-mail: diomedes@ufpa.br Em uma propriedade localizada na região nordeste do Estado do Pará foram analisadas alternativas de suplementação mineral para bovinos de corte, da raça nelore, machos, com idades entre 18 e 20 meses e pesos de 299,5 a 308,5 kg. Foram avaliados o custo benefício, os valores dos minerais no fígado e nas costelas e o ganho de peso médio diário dos animais submetidos aos diferentes tratamentos. O estudo foi realizado durante seis meses (março a agosto de 2012), no período de ótima oferta de pastagem. Foram utilizados 60 bovinos, divididos em três grupos de 20 animais em delineamento experimental inteiramente casualizado. O Grupo 1 foi suplementado com uma mistura mineral seletiva (MMS) composta por 25kg de NaCl, 50kg de fosfato bicálcico,190g de sulfato de Cobre, 60g de sulfato de Cobalto e 15g de selenito de sódio; essa mistura continha, em um quilograma, 133g de Na, 123g de P, 631 mg de Cu, 167mg de Co e 9 mg de Se; essa mistura foi proposta com base no prévio diagnóstico clínico-nutricional do rebanho. O Grupo 2 foi suplementado apenas com NaCl (Grupo controle) e o Grupo 3 recebeu uma mistura mineral comercial (MMC), rotineiramente utilizada na fazenda, contendo, em um quilograma, 130g de P, 220g de Ca, 18g de Mg, 36g de S, 6.000mg de Zn, 1.500mg de Cu, 2.000mg de Mn, 200mg de Co, 90mg de I e 36mg de Se. O melhor custo benefício foi obtido com a mistura mineral seletiva. A pastagem não contém Co suficiente para atender as necessidades dos bovinos do grupo controle, mas foi capaz de suprir as necessidades de P, Cu, Zn e Se durante os cinco meses do experimento.

Abstract in English:

ABSTRACT.- Malafaia P., Costa R.M., Brito M.F., Peixoto P.V., Barbosa J.D., Tokarnia C.H. & Döbereiner J. 2014. [Erroneous interpretations regarding mineral deficiencies and supplementation of cattle in Brazil.] Equívocos arraigados no meio pecuário sobre deficiências e suplementação minerais em bovinos no Brasil. Pesquisa Veterinária Brasileira 34(3):244-249. Departamento de Nutrição Animal e Pastagem, Instituto de Zootecnia, Universidade Federal Rural do Rio de Janeiro, BR 465 Km 7, Seropédica, RJ 23890-000, Brazil. E-mail: malafaia_ufrrj@yahoo.com.br The economic importance of mineral deficiencies in cattle and their supplementation for animal health and production is well established. But in spite of the existing knowledge and conscience of professionals on this subject in Brazil, there are numerous erroneous interpretations and superstitions on mineral supplementation for cattle, together with indiscriminate commercialization of mineral mixtures; the latter, thoroughly accepted and applied in the rural area, causes considerable economic losses to the cattle industry. In this article of general interest we discuss, one by one, the most important misunderstandings and superstitions regarding this subject.

• Mineral deficiencies mineral supplementation deficiências minerais suplementação mineral

Abstract in Portuguese:

RESUMO.- Malafaia P., Costa R.M., Brito M.F., Peixoto P.V., Barbosa J.D., Tokarnia C.H. & Döbereiner J. 2014. [Erroneous interpretations regarding mineral deficiencies and supplementation of cattle in Brazil.] Equívocos arraigados no meio pecuário sobre deficiências e suplementação minerais em bovinos no Brasil. Pesquisa Veterinária Brasileira 34(3):244-249. Departamento de Nutrição Animal e Pastagem, Instituto de Zootecnia, Universidade Federal Rural do Rio de Janeiro, BR 465 Km 7, Seropédica, RJ 23890-000, Brazil. E-mail: malafaia_ufrrj@yahoo.com.br Está bem estabelecida a importância que as deficiências e a suplementação minerais exercem na sanidade, produtividade e economicidade da atividade pecuária brasileira. Apesar de os conhecimentos sobre este assunto no meio acadêmico no Brasil serem sólidos, há numerosos equívocos e crendices sobre a suplementação mineral, aliados à comercialização indiscriminada de suplementos minerais, amplamente aceitos e aplicados no meio rural, o que causa consideráveis prejuízos ao setor pecuário. Neste artigo de interesse geral são discutidos, um por um, as mais importantes interpretações errôneas a respeito desse tema.

Abstract in English:

ABSTRACT.- Malafaia P., Cruz P.B. & Silva V.P. 2014. [Milk production, composition and body condition score of lactating goats receiving two types of mineral mixtures.] Produção e composição do leite e escore corporal de cabras lactantes submetidas à suplementação mineral comercial e seletiva. Pesquisa Veterinária Brasileira 34(2):119-122. Departamento de Nutrição Animal e Pastagem, Instituto de Zootecnia, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23851-970, Brazil. E-mail: malafaia_ufrrj@yahoo.com.br Comparison of milk production and composition, body condition score and the cost of commercial or selective mineral supplementation was made using two groups of 16 lactating goats during 164 days. No significant difference in milk production between treatments was found. There was no effect of the type of mineral supplement on the composition of milk fat, protein and lactose as well as on the somatic cell count (SCC). The average of daily intake of the commercial supplement was 1.76 times greater than the supplement containing only sodium chloride associated with copper sulfate. The use of the selective mineral mixture based on clinical-nutritional examination of the animals led to a reduction of about 7 times the amount spent by mineral supplementation of this goat herd.

• Milk mineral deficiencies mineral supplementation leite deficiências minerais suplementação mineral

Abstract in Portuguese:

RESUMO.- Malafaia P., Cruz P.B. & Silva V.P. 2014. [Milk production, composition and body condition score of lactating goats receiving two types of mineral mixtures.] Produção e composição do leite e escore corporal de cabras lactantes submetidas à suplementação mineral comercial e seletiva. Pesquisa Veterinária Brasileira 34(2):119-122. Departamento de Nutrição Animal e Pastagem, Instituto de Zootecnia, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23851-970, Brazil. E-mail: malafaia_ufrrj@yahoo.com.br A comparação da produção e composição do leite, do escore corporal e dos custos com a suplementação mineral comercial e seletiva foi feita utilizando-se dois grupos de 16 cabras lactantes por 164 dias. Não houve diferenças significativas na produção de leite dos animais que ingeriram os dois tipos de suplementos minerais. Não houve efeito do tipo de suplementação mineral em relação a composição do leite em gordura, proteína e lactose bem como na contagem de células somáticas (CCS). O consumo médio diário do suplemento comercial foi 1,76 vezes maior do que o suplemento contendo apenas cloreto de sódio associado ao sulfato de cobre. A utilização da mistura mineral seletiva, formulada com base no exame clínico-nutricional dos animais, gerou uma redução de aproximadamente 7 vezes o custo com a suplementação mineral do rebanho caprino.

Abstract in English:

Peixoto P.V., Malafaia P., Barbosa J.D. & Tokarnia C.H. 2005. [Principles of mineral supplementation in ruminants.] Princípios de suplementação mineral em ruminantes. Pesquisa Veterinária Brasileira 25(3):195-200. Depto Nutrição Animal e Pastagem, Instituto de Zootecnia, UFRRJ, Km 47, Seropédica, RJ 23890-000, Brazil. E-mail: pfpeixoto@terra.com.br Although there is solid knowledge on mineral deficiencies and their consequences on health and productivity of cattle in Brazil, paradoxically, those informations, most of the time, are not used by professionals of the agricultural sciences, who persist in stimulating the widespread use of the so-called complete mineral mixtures. The deficiency of many minerals included in these supplements, as iron, chrome, sulfur, and others, do not occur under natural conditions or only in rare and very particular situations. The present paper deals with the misunderstandings and problems related to traditional mineral supplementation and discusses the main aspects of the so-called selective mineral supplementation that is based in supplying exclusively the deficient mineral(s) and these only in necessary amounts. This procedure can result in expressive economy (sometimes up to 700%) when compared with the commercial mineral supplementation usually employed. According to several estimates, mineral supplementation can account for 20 to 30% of the total cost of beef cattle production on tropical pastures. A reversion assay, in which a group of cattle receives the commercial mineral mixture routinely used on the farm, and another group which receives the selective supplement, is the best option for the elucidation of positive or negative effects between the two possibilities of mineral supplementation on a specific farm. Trough this assay, the effects of the two compositions of mineral supplements can be investigated rationally over a sufficient period of time, with no risks and minimal possibilities of economic losses.

• Mineral deficiencies mineral supplementation ruminants cattle.

Abstract in Portuguese:

Peixoto P.V., Malafaia P., Barbosa J.D. & Tokarnia C.H. 2005. [Principles of mineral supplementation in ruminants.] Princípios de suplementação mineral em ruminantes. Pesquisa Veterinária Brasileira 25(3):195-200. Depto Nutrição Animal e Pastagem, Instituto de Zootecnia, UFRRJ, Km 47, Seropédica, RJ 23890-000, Brazil. E-mail: pfpeixoto@terra.com.br Although there is solid knowledge on mineral deficiencies and their consequences on health and productivity of cattle in Brazil, paradoxically, those informations, most of the time, are not used by professionals of the agricultural sciences, who persist in stimulating the widespread use of the so-called complete mineral mixtures. The deficiency of many minerals included in these supplements, as iron, chrome, sulfur, and others, do not occur under natural conditions or only in rare and very particular situations. The present paper deals with the misunderstandings and problems related to traditional mineral supplementation and discusses the main aspects of the so-called selective mineral supplementation that is based in supplying exclusively the deficient mineral(s) and these only in necessary amounts. This procedure can result in expressive economy (sometimes up to 700%) when compared with the commercial mineral supplementation usually employed. According to several estimates, mineral supplementation can account for 20 to 30% of the total cost of beef cattle production on tropical pastures. A reversion assay, in which a group of cattle receives the commercial mineral mixture routinely used on the farm, and another group which receives the selective supplement, is the best option for the elucidation of positive or negative effects between the two possibilities of mineral supplementation on a specific farm. Trough this assay, the effects of the two compositions of mineral supplements can be investigated rationally over a sufficient period of time, with no risks and minimal possibilities of economic losses.

Abstract in English:

Malafaia P., Pimentel V.A., Freitas K.P., Coelho C.D., Brito M.F. & Peixoto P.V. 2003. [Daily weight gain, economic, nutritional and clinical aspects of goats receiving two types of mineral supplements.] Desempenho ponderal, aspectos econômicos, nutricionais e clínicos de caprinos submetidos a dois esquemas de suplementação mineral. Pesquisa Veterinária Brasileira 24(1):15-22. Depto de Nutrição Animal e Pastagem, Instituto de Zootecnia, UFRRJ, Km 47, Seropédica, RJ 23835-000, Brazil. E-mail: malafaia1@ig.com.br Daily weight gain, economic, nutritional and clinical aspects of goats receiving two types of mineral supplements were evaluated during 148 days in Seropédica county, Rio de Janeiro, Brazil. The animals were daily fed with fresh and chopped Andropogon gayanus or Pennisetum purpureum; the concentrate ration was formulated without a mineral mixture and was offered together with the forage of 300 up to 500 g/animal/day. Sixteen goats were divided into two groups of 8 animals each (4 small and 4 larger goats). For one group a commercial mineral mixture was used, and to the other group a selective mineral mixture containing only Na, P and Cu was offered. The animals were weighed every 30 days and the mineral supplement intake was measured monthly. Blood samples were collected at the beginning and the end of the experimental period. There was no difference in daily weight gain when the selective or commercial mixture was given for both groups. The selective mineral supplementation was 2.3 (for the smaller animals) and 3.9 (for larger animals) times more economic than the conventional supplementation with a “complete” mineral mix. The two groups showed recovery of hair quality and had an increase of hair pigmentation around the eyes, which was attributed to the correction of copper deficiency. In the larger animals the intake of both supplements increased the red blood cells counts, and the haematocrit and haemoglobin values. The forage intake was sufficient to meet the Ca and Co needs of the animals, and for P the concentrate intake was sufficient to overcome the demand for this element. The requirement of zinc was supplied through the forage and the concentrate ration. Thus, when an adequate concentrate and a good quality forage is given, only the deficient mineral element(s) should be supplemented. In this specific case only Na and Cu should be given. The result of this experiment confirms the hypothesis that selective mineral supplementation – i.e. supplementation of the mineral element(s) deficient in the diet – was correct and can result in reduction of the cost with the mineral supplementation of a herd.

• Goats copper deficiency mineral supplementation tropical forages.

Abstract in Portuguese:

Malafaia P., Pimentel V.A., Freitas K.P., Coelho C.D., Brito M.F. & Peixoto P.V. 2003. [Daily weight gain, economic, nutritional and clinical aspects of goats receiving two types of mineral supplements.] Desempenho ponderal, aspectos econômicos, nutricionais e clínicos de caprinos submetidos a dois esquemas de suplementação mineral. Pesquisa Veterinária Brasileira 24(1):15-22. Depto de Nutrição Animal e Pastagem, Instituto de Zootecnia, UFRRJ, Km 47, Seropédica, RJ 23835-000, Brazil. E-mail: malafaia1@ig.com.br Daily weight gain, economic, nutritional and clinical aspects of goats receiving two types of mineral supplements were evaluated during 148 days in Seropédica county, Rio de Janeiro, Brazil. The animals were daily fed with fresh and chopped Andropogon gayanus or Pennisetum purpureum; the concentrate ration was formulated without a mineral mixture and was offered together with the forage of 300 up to 500 g/animal/day. Sixteen goats were divided into two groups of 8 animals each (4 small and 4 larger goats). For one group a commercial mineral mixture was used, and to the other group a selective mineral mixture containing only Na, P and Cu was offered. The animals were weighed every 30 days and the mineral supplement intake was measured monthly. Blood samples were collected at the beginning and the end of the experimental period. There was no difference in daily weight gain when the selective or commercial mixture was given for both groups. The selective mineral supplementation was 2.3 (for the smaller animals) and 3.9 (for larger animals) times more economic than the conventional supplementation with a “complete” mineral mix. The two groups showed recovery of hair quality and had an increase of hair pigmentation around the eyes, which was attributed to the correction of copper deficiency. In the larger animals the intake of both supplements increased the red blood cells counts, and the haematocrit and haemoglobin values. The forage intake was sufficient to meet the Ca and Co needs of the animals, and for P the concentrate intake was sufficient to overcome the demand for this element. The requirement of zinc was supplied through the forage and the concentrate ration. Thus, when an adequate concentrate and a good quality forage is given, only the deficient mineral element(s) should be supplemented. In this specific case only Na and Cu should be given. The result of this experiment confirms the hypothesis that selective mineral supplementation – i.e. supplementation of the mineral element(s) deficient in the diet – was correct and can result in reduction of the cost with the mineral supplementation of a herd.

Abstract in English:

ABSTRACT.- Peixoto P.V., Malafaia P., Miranda L.V., Canella C.F.C., Canella Filho, C.F.C. & Villas Boas F.V. 2003. [Reproduction performance of beef cattle cows given three different types of mineral supplements.] Eficiência reprodutiva de matrizes bovinas de corte submetidas a três diferentes tipos de suplementação mineral. Pesquisa Veterinária Brasileira 23(3):125-130. Depto Nutrição Animal e Pastagem, Inst. Zootecnia, UFRRJ, Km 47, Seropédica, RJ 23851-970, Brazil. E-mail: pvpeixoto@uol.com.br The reproduction performance of about 1,200 beef cows, raised on pasture and given three different mineral supplements, was evaluated during 5 years in Cássia county, Minas Gerais, Brazil. The cows were divided into three groups: For one group (A) a comercial mineral mixture was used in 1997 and 1998; for the second group (B) common salt and dicalcium phosphate 1:1 was offered in 1999; and the third group (C) received only common salt during the sarne year. ln 2000 and 2001, ali the cows received exclusively common salt. There was no decrease in i:eproduction efficiency when only common salt was given; on the contrary, the reproduction performance of the inseminated e pregnant cows, thát was respectively 92.5 and 78.2 % (1997) and 92.2 and 80.5 % (1998), increased to 94.5 and 85.7 % (2000) and 96.7 and 89.7 % (2001). The decrease of reproduction performance of the cattle in 1999 was probably due to the severe drought during this year. The authors emphasize the importance of a selective mineral supplementation, i.e. to supplement cattle with mineral mixtures including only the elements which the animais can not obtain from the pasture. Theselective mineral supplementation requires the assistance of professionals with training and experience in clinics, pathology and nutrition of ruminants. These professionals should be able to accompany and evaluate the nutritional condition of a herd when a selective mineral mixture is used. Selective mineral supplementation could represent a two or threefold economy of the total cost of conventional supplementation with "complete" mineral mixtures. The authors discuss ifthe improvement of the reproduction performance of the cattle used in this fiel d experiment was due to a better management of the herd or to possible antagonism between the minerais.

• Cattle mineral deficiencies mineral supplementation tropical pastures Bovinos deficiências minerais pastagens tropicais suplementação mineral.

Abstract in Portuguese:

RESUMO.- Peixoto P.V., Malafaia P., Miranda L.V., Canella C.F.C., Canella Filho, C.F.C. & Villas Boas F.V. 2003. [Reproduction performance of beef cattle cows given three different types of mineral supplements.] Eficiência reprodutiva de matrizes bovinas de corte submetidas a três diferentes tipos de suplementação mineral. Pesquisa Veterinária Brasileira 23(3):125-130. Depto Nutrição Animal e Pastagem, Inst. Zootecnia, UFRRJ, Km 47, Seropédica, RJ 23851-970, Brazil. E-mail: pvpeixoto@uol.com.br Em uma fazenda do município de Cássia, Minas Gerais, o desempenho reprodutivo de aproximadamente 1200 matrizes bovinas de corte, criadas a campo, foi avaliado frente a três diferentes tipos de suplementação mineral, durante cinco anos. Enquanto que a mistura A (sal mineral comercial) foi oferecida nos anos de 1997 e 1998, a mistura B (cloreto de sódio 50% e fosfato bicálcico 50%) foi disponibilizada, em 1999, para as matrizes mantidas em um dos setores da fazenda e a mistura C (apenas cloreto de sódio), foi oferecida, neste mesmo ano, para os lotes cria dos em outros dois setores. Nos anos de 2000 e 2001, a mistura C foi ofertada a todas matrizes. Não houve queda na eficiência reprodutiva pela suplementação exclusiva com cloreto de sódio, pelo contrário, as percentagens de matrizes inseminadas e matrizes prenhes, que eram, respectivamente, de 92,5 e 78,2 (1997) e 92,2 e 80,5 (1998) alcançaram níveis de 94,5 e 85,7 (2000) e 96,7 e 89,7 (2001). A redução nos índices de matrizes inseminadas e de prenhez verificadas no ano de 1999 foi atribuída à baixa precipitação pluviométrica registrada naquele ano. Os autores ressalvam, porém, que a suplementação seletiva, isto é, aquela baseada na exclusiva administração do (s) mineral (is) que está (ão) faltando em uma determinada fazenda, só deve ser implantada mediante avaliação e acompanhamento clínico-nutricional do rebanho, o que exige apoio de profissional com adequados conhecimentos sobre nutrição, deficiências minerais e clínica de ruminantes. Por outro lado, a suplementação seletiva, pode representar uma despesa 2 a 3 vezes menor do que a verificada com a "mineralização" convencional do rebanho. Discute-se se a melhoria dos índices reprodutivos deveu-se à adequação do manejo ou à cessação de possível antagonismo entre os minerais.