Intact Calves Research Articles

Minimally Invasive Surgical Versus Ultrasound Guided Inguinal Tube Cystostomy for Management of Obstructive Urolithiasis in Cattle

Background: Tube cystostomy, though a popular technique to relieve obstructive urolithiasis in ruminants with advantages of lower recurrences, preservation of the reproductive function of the animal and restoration of full urethral patency in successful cases, is time consuming and invasive. Tube cystostomy performed under ultrasound guidance is hypothecated to be technically easier, safer and quicker. Methods: Twelve bovine intact male calves of 3-9 months age with obstructive urolithiasis were divided into two groups of six animals each. One group was subjected to surgical and another ultrasound guided minimally invasive tube cystostomy through the inguinal approach. In group A animals, after exposing the bladder throughthe grid incision, the catheter was placed in the bladder lumen, using teat tumor extractor fixed in the eye of the Foley’s catheter. In group B animals tube cystostomy under ultrasound guidance was performed through in the skin. Incision was closed as per routine. Techniques were evaluated on the basis of various parameters like, technical feasibility, use of anesthesia, use of suture material, time taken for surgery, haematobiochemical parameters, time taken for normal urination, survival rate and intra and postoperative complications. Result: Ultrasound guided minimally invasive inguinal tube cystostomy technique was not only technically easier to perform but also required lesser time, lesser suture material with quicker onset of normal urination Obstruction of catheter occurred in one animal of each group. Survival rate of 67% without any complication was recorded in both groups.

THE EFFICACY OF OXYTETRACYCLINE THERAPY AND THE DURATION OF TREATMENT IN THE COURSE OF BOVINE ANAPLASMOSIS

A total of 27 crossbred calves (12 intacts, 9 splenec­tomised and 6 uninfected control) were sub­cutaneously Inoculated with 2 x 107 Anaplasma marginale infected erythrocytes. Oxytetracycline (at 10mg/kg body weight) was administered in­travenously when the PCV dropped to 16 per cent or below. The pattern of development of parasitaemia, appeared to be similar in both intact and splenec­tomised calves. The spelectomised calves, however, gave higher percentage of parasitaemia. Fluctuation in the PCV followed the same pattern in both groups, but the splenectomised calves were observed to suffer more anaemic crisis than the intact ones. In the intact calves, all those treated once and for 2 consecutive days survived. In the splenectomised calves, all those treated once died, while all those treated for 2 consecutive days survived. It may be concluded that, 2 consecutive ox­ytetracycline treatments (at 10mg/kg body weight) gave better recovery rates in cases of clinical bovine anaplasmosis.

Incorporating oldman saltbush hay and prickly pear in diets for red Sindhi calves

This study was designed to evaluate the nutrient intake, digestibility, degradability, and ruminal characteristics of Sindhi heifers fed diets that contained a combined total of 75% oldman saltbush hay (hereafter saltbush hay) and prickly pear cactus. Eight 12-month old intact male red Sindhi calves (four fistulated and four non-fistulated) with an initial mean weight of 170 ± 5 kg were assigned to 4 × 4 Latin squares, where factors consisted of four diets, namely 15% hay and 60% cactus; 30% hay and 45% cactus; 45% hay and 30% cactus; and 60% hay and 15% cactus, and four times at which rumen fluid was collected. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) intakes in kg/day and NDF in percentage live weight (LW), water intake, salinity, and conductivity increased with hay level. Intake and digestibility of non-fibrous carbohydrates were curvilinear with higher values in diets containing 30% saltbush hay. The apparent digestibility of dry matter (DM) and organic matter decreased linearly as the concentration of saltbush hay increased in the diet. The pH of the rumen fluid was within the acceptable range for favourable microbial growth. The low temperature and high salinity and conductivity indices in the diets should be viewed with caution at higher concentrations of saltbush hay, because of a possible decrease in nutrient absorption and the development of health problems in the animals. Apparent degradability coefficients of DM and NDF were affected significantly by inclusion of prickly pear and saltbush hay in the diets.Keywords: animal nutrition, apparent digestibility, Atriplex nummularia Lindl, Opuntia ficus, ruminal degradation, semi-arid environment

Chemical castration in cattle with intratesticular injection of sodium chloride: Effects on stress and inflammatory markers

Intratesticular injection (ITI) of sodium chloride (NaCl) is efficient for chemical castration of young calves, but its effects on calves welfare are unknown. Two experiments were conducted to evaluate the effects of ITI of 20% NaCl on stress and inflammatory markers in calves less than 20 days old and to assess the efficiency of ITI of 30% NaCl in 5 months old calves. In Experiment 1, control calves were only restrained and compared to calves submitted to castration through surgery (SC) and ITI with 20% NaCl (n = 9/group). No differences were observed for the eye corner temperature measured by thermography from 60 s before to 60 s after the procedures (P > 0.05). In the SC group, acute serum cortisol levels increased at 30 and 60 min after the procedure, but increased levels in the ITI group occurred only at 30 min (P < 0.05). Chronic discomfort markers were measured at 0, 24, 48, 72 and 96 h after the procedures (D0, D1, D2, D3 and D4, respectively). The serum levels of the paraoxonase 1 (PON1) enzyme and cortisol did not differ among groups (P > 0.05). Scrotal temperature was higher at D1 in the SC group than for the other groups, but lowest at D4 compared to the control (both P < 0.05). In Experiment 2, histological sections of testes were compared after ITI with either 30% NaCl or 30% calcium chloride (CaCl2), to intact calves (control). After 60 days, intact seminiferous tubules and mediastinum were observed after ITI with 30% NaCl, whereas coagulative necrosis, inflammatory infiltration and calcification occurred after ITI with 30% CaCl2. Efficient chemical castration through ITI of 20% NaCl in young calves was followed by slight stress and inflammatory responses compared to surgical castration. However, ITI of 30% NaCl was ineffective for chemical castration of 5 months old calves.

Ganancia de peso diaria de machos castrados vs. machos enteros durante la recría

The study was conducted in Osorno Chile, in order to assess the effect of castration on average daily gain of weaned calves during the backgrounding phase. The study considered a total of 20 weaned calves of a beef biotype whose average live weight was 189.5 kg (± 4.3 SEM). Two groups of 10 animals each were randomly assigned to two treatments consisted in calves castrated after weaned and intact calves. Both groups were handled similarly; grazing natural pastures composed mainly of Trifolium repens L., Achillea millefolium L. and Anthoxanthum odoratum L. The study was conducted as a completely randomized design, with each animal being considered as experimental and observational unit. Data were analyzed using the statistical package JMP (SAS Institute, N.C. USA) by using a covariance analysis (ANCOVA by initial body weight) with a significance level of 5%. The evaluation period was 90 days and animals were weighted fortnightly. Total weight gains during the study period were 113.6 y 117.6 kg (± 5.7 SEM) for castrated and intact calves, respectively. No differences were observed between average daily weight gain (castrated = 1.27 vs. intact = 1.30 kg/d ± 0.06 kg/d). We conclude that there are no productive advantages by keeping intact animals, thereby increasing the risk of stress, suffering and risk of operators to perform the castration.

Loss of neurovirulence is associated with reduction of cerebral capillary sequestration during acute Babesia bovis infection

BackgroundSevere neurological signs that develop during acute infection by virulent strains of Babesia bovis are associated with sequestration of infected erythrocytes in cerebral capillaries. Serial passage of virulent strains in cattle results in attenuated derivatives that do not cause neurologic disease. We evaluated whether serial passage also results in a loss of cerebral capillary sequestration by examining brain biopsies during acute disease and at necropsy.FindingsCerebral biopsies of spleen intact calves inoculated intravenously with a virulent or attenuated strain pair of B. bovis were evaluated for capillary sequestration at the onset of babesiosis and during severe disease. In calves infected with the virulent strain, there was a significant increase in sequestration between the first and second biopsy timepoint. The attenuated strain was still capable of sequestration, but at a reduced level, and did not change significantly between the first and second biopsy. Necropsy examination confirmed the second biopsy results and demonstrated that sequestration identified at necropsy reflects pathologic changes occurring in live animals.ConclusionsLoss of neurovirulence after serial in vivo passage of the highly virulent T2Bo strain of B. bovis in splenectomized animals is associated with a significant reduction of cerebral capillary sequestration. Previous genomic analysis of this and two other strain pairs suggests that this observation could be related to genomic complexity, particularly of the ves gene family, rather than consistent gene specific differences. Additional experiments will examine whether differential gene expression of ves genes is also associated with reduced cerebral sequestration and neurovirulence in attenuated strains.

Effects of Burdizzo castration on CO 2 laser induced thermal nociception of Holstein–Friesian calves of different ages

The objective was to investigate the effects of Burdizzo castration on the thermal nociception (stress-induced hypoalgesia) of Holstein–Friesian bull calves of different ages. Calves castrated at 5.5 mo of age were compared with either intact calves of the same age, or calves castrated at 1.5, 2.5, 3.5, and 4.5 mo of age ( n = 10 calves/treatment). Treatments were conducted on the same day for all calves. The baseline surface skin temperatures on the caudal part of metatarsi, and the latency of the calves to perform hind leg withdrawal (i.e., thermal nociception threshold) in response to a CO 2 laser beam applied on the same area were measured 72 h before, and 12, 24 and 48 h after treatment. The thermal nociception threshold varied inversely with the baseline skin temperature (pooled correlations, r = −0.45, −0.31 and −0.48 at 12, 24 and 48 h, respectively; P < 0.01). There were no differences ( P > 0.05) in the skin temperatures between castrated and intact calves at 5.5 mo of age. Calves castrated at 1.5 mo-old had consistently lower skin temperatures than all other castrated calves throughout the study. These calves had markedly increased skin temperatures following castration, while the opposite trend was observed in older castrated calves, and no change was observed in intact calves. At −72 h, the 1.5 mo-old calves had higher thermal nociception thresholds than older calves. In all calves, the thermal nociception threshold increased after treatment. Calves castrated at 5.5 mo of age tended to display higher thermal nociception threshold than intact calves. However, variations in the initial skin temperature accounted for these differences between treatments or interactions between time and treatment. In conclusion, the laser-based thermal nociception assay can be influenced by the surface skin temperature of the hind legs and the age of animals, particularly in calves less than 2 mo of age which have lower skin temperatures and longer latency to respond to the laser. Burdizzo castration increased the skin temperature of 1.5 mo-old calves, but had the opposite effects on older calves. Within the temporal limits of this study, no conclusive evidence was found to support the presence of acute stress-induced hypoalgesia following castration.

Effects of ring castration with local anesthesia and analgesia in Holstein calves at 3 months of age on welfare indicators1

Forty-seven Holstein calves (130 +/- 3.43 kg of BW and 95 +/- 1.5 d of age) were randomly assigned to 2 treatments [intact (INT), n = 23; or castrated (CAS), n = 24] to evaluate the effect of ring castration at 3 mo of age on welfare indicators. Castration was performed with local anesthesia (2% lidocaine, 3 mL in each testis and 2 mL in the scrotum) and analgesia (flunixin meglumine, intramuscularly, 3 mg/kg of BW). No local anesthesia or analgesia was used with INT calves. Serum cortisol concentration was determined at -120, 0, 30, 60, 90, and 180 min with respect to castration. At d 0, 1, 3, 7, 14, 21, 28, 35, 42, and 49, serum haptoglobin concentration was determined, rectal body and scrotal temperatures were measured, lesions at the castration site were scored, and the activity and behavior of 18 calves (9 INT and 9 CAS) were recorded continuously for 24 h. Weekly BW and concentrate and straw DMI were recorded. To evaluate humoral immunity, at 14 d after castration, ovalbumin was injected subcutaneously and serum antibody titers against ovalbumin before the injection and at d 35 were determined. At d 49 after castration, calves were intravenously injected with ACTH, and at 0, 1, 2, and 4 h thereafter, serum cortisol and testosterone concentrations were determined. Average daily gain was greater (P < 0.001) in INT than CAS calves (1.36 vs. 1.16 +/- 0.038 kg/d, respectively). Area under the curve of cortisol at castration day was reduced (P < 0.05) in CAS calves compared with INT calves (18 vs. 33 +/- 5.2 nmol/L per hour, respectively). The main scrotal lesion score observed in CAS calves throughout the study was 0, corresponding to no visible swelling, inflammation, or infection. However, scrotal lesion scores classified as 1 (swelling) were greater (P < 0.01) at 21 and 28 d after castration than at 1, 3, 7, and 14 d. Abnormal standing occurred more frequently (P < 0.001) in CAS than INT calves (2.6 vs. 0.5 +/- 0.03%, respectively) from 3 to 14 d after castration. Head turning tended (P = 0.06) to be greater at d 14 of the study in CAS than INT calves (3.0 vs. 2.6 +/- 0.04%, respectively). At d 49, 100% of CAS calves had no testes and no serum testosterone was detected. In summary, ring castration of Holstein calves performed at 3 mo of age with local anesthesia and analgesia decreased ADG and affected some behavioral traits during the first 14 d after castration. However, intake, serum cortisol and haptoglobin concentrations, rectal temperature, and humoral immunity were not altered.

Effects of age of Holstein-Friesian calves on plasma cortisol, acute-phase proteins, immunological function, scrotal measurements and growth in response to Burdizzo castration

AbstractTo determine the effect of age at castration on physiological and immunological stress indices, 60 Holstein-Friesian bull calves were sourced so that they were in one of five age groups for Burdizzo castration on day 0 (16 July 2002; no. = 10 per treatment) : 1·5, 2·5, 3·5, 4·5, and 5·5 months of age (mean body weight ± s.e. = 63 ± 2·5, 89 ± 3·7, 104 ± 3·7, 142 ± 3·6, 169 ± 8·1 kg, respectively), or were sham castrated at 5·5 months of age (171 ± 2·9 kg body weight) to serve as intact controls specific to this age group. Blood samples were collected at 15- to 30-min intervals from 2 h before until 8 h after treatment, with further samples collected at 10 and 12 h on day 0, and on days 1, 2 and 3, and weekly from days 7 to 35 after treatment. Following castration, peak plasma cortisol responses were significantly greater in 5·5-month-old castrates than intact calves, and all calves castrated at a younger age had reduced peak responses, with the greatest reduction in 1·5-month-old castrates. Overall, the integrated cortisol responses for the first 3 h after castration were three-fold greater in 5·5-month-old castrates than intact calves. While the integrated cortisol responses were reduced by proportionately 0·46 and 0·35 in 1·5- and 4·5-month-old castrates, the lower responses observed in 2·5- and 3·5- month-old castrates were not significantly different from the 5·5-month-old castrates. The integrated cortisol responses for the next 9 h after castration were not different among treatment groups. On day 3 after castration, peak plasma haptoglobin and fibrinogen concentrations were significantly greater in 5·5-month-old castrates than intact calves, but the concentrations were markedly reduced in calves castrated at 1·5 and 2·5 months than when castrated at 5·5 months of age. On day 1, phytohaemagglutinin-inducedin vitrointerferon-γ production was suppressed in 5·5-month-old castrates compared with intact calves. Scrotal circumferences increased in all castrates on day 1 and 7 and were greater in 5·5- month-old castrates than intact calves, but the swelling was reduced in the 1·5- compared with 5·5-month-old castrates. The temperature differences between the core body and scrotal skin were greater on day 2 and 3 in the 1·5-month-old than all other castrates. There was no effect of castration on the overall 42-day growth rates of calves. In conclusion, the physiological stress and inflammation caused by Burdizzo castration, indicated by increased plasma cortisol, acute-phase proteins, scrotal swelling, and depressed temperature differences between the core body and scrotal skin were reduced by castrating calves at 1·5 months rather than at 5·5 months of age.

Effect of Gossypol from Cottonseed Meal Diets on Some Clinico-biochemical Parameters and Humoral Immune Response of Crossbred Calves Fed Barley or Sorghum

Effects of feeding of 9.95 mg free gossypol/kg live weight through cottonseed meal (CSM) were studied in 20 intact male calves fed barley or sorghum as source of cereal during the experimental duration of 210 days. Serum concentration of total protein, albumin, globulin and their ratio did not vary because of protein (gossypol) or cereal sources. Serum level of cholesterol and urea were lower (p<0.05) in sorghum than barley fed calves. Feeding of gossypol through CSM enhanced (p<0.05) serum cholesterol. An interaction between protein and period was observed with respect to serum concentrations of urea, creatinine and alanine transferase. The levels of serum creatinine and alanine transferase increased (p<0.05) following 120 days of experimental feeding in calves fed CSM diets compared to the control animals fed groundnut meal diets. No effect of feeding gossypol was, however, evident on the serum enzymes viz. alanine and aspartate transferases and alkaline phosphatase. Moreover, the source of cereal and protein did not appear to influence the metabolic profile of the calves. Humoral immune response, measured through antibody titre against Brucella abortus S99 innoculation, revealed a delayed and depressed seroreactivity indicative of immunocompromisation because of the phytotoxin gossypol. In conclusion, the feeding of gossypol at the designated levels, although had no deleterious clinico-biochemical manifestations, affected the humoral immune response of the calves. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 9 : 1291-1296)

Tissue lactate dehydrogenase patterns of calves with total artificial hearts

The objective of this study was to evaluate, compare, and contrast the tissue lactate dehydrogenase (LD) patterns of calves with total artificial hearts (TAH). The tissue LD patterns of six calves with TAHs surviving 97 to 218 days and two calves with TAHs from short-term experiments were compared with those of control intact calves. LD patterns in the same kind of tissue, expressing the extent of tissue damage, were compared between experiments. From 38 analyzed tissue samples, only 4 or 10 fell within the reference values of the control group (mean ± 2s x,y or mean ± 3s x,y ), respectively. Each of the calves with a TAH had a unique order of the differences of experimental tissue LD patterns from control data. The relative cumulative order of the differences from controls was spleen < kidney < liver < left atrium < lung < right atrium. Determination of the tissue LD pattern may become an additional diagnostic tool complementary to microscopic examination of samples.

Substituição do Milho pela Farinha de Varredura (Manihot esculenta, Crantz) na Ração de Bezerros Holandeses.: 1. Desempenho e Parâmetros Sangüíneos

O objetivo deste trabalho foi avaliar o efeito de diferentes níveis de substituição do milho pela farinha de varredura de mandioca (0, 25, 50, 75 e 100%, base da matéria seca), sobre o consumo e conversão alimentar, ganho médio diário e níveis de hematócrito, glicose e uréia sanguíneos. Utilizaram-se 35 bezerros holandeses puros de origem ou puros por cruzamento, não castrados, com idade aproximada de 80 dias e peso vivo médio de 80 kg, distribuídos em delineamento de blocos casualizados. Os animais foram alimentados à vontade, até atingir o consumo de 4 kg/dia de concentrado. Como volumoso, foi utilizado feno inteiro de capim tifton 85. Os animais terminaram o experimento, com peso médio de 164 kg. A elevação dos níveis de substituição ocasionou uma resposta linear decrescente no consumo de matéria seca. A conversão alimentar não diferiu entre os tratamentos. Os ganhos diários para os dois primeiros períodos de 28 dias reduziram-se linearmente, com a elevação dos níveis de substituição, mas não diferiram no último período de 28 dias, apresentando valores estimados, variando de 0,93 a 0,68, 1,10 a 0,89 e 1,09 kg/dia, respectivamente. Os níveis de hematócrito, glicose e uréia não foram influenciados pelos níveis de substituição do milho pela farinha de varredura.

Substituição do Milho pela Farinha de Varredura (Manihot esculenta, Crantz) na Ração de Bezerros Holandeses.: 2. Digestibilidade e Valor Energético

Foram utilizados 20 bezerros holandeses, não castrados, com idade média de 160 dias e peso vivo inicial de 163 kg, em delineamento inteiramente casualizado, para avaliar o efeito de cinco níveis de substituição (0, 25, 50, 75 e 100% na base da matéria seca) do milho pela farinha de varredura de mandioca sobre o consumo e digestibilidade aparente da matéria seca, proteína bruta, fibra em detergente neutro, amido e energia bruta. Não houve efeito dos níveis de substituição do milho pela farinha de varredura no consumo de matéria seca. O aumento dos níveis de farinha de varredura nas dietas proporcionou aumento linear dos coeficientes de digestibilidade aparente da matéria seca, proteína bruta, amido e energia bruta, mas não influenciou o da fibra em detergente neutro. Não houve efeito da substituição do milho pela farinha de varredura nos valores energéticos das rações.

Influência do Plano Nutricional sobre o Desempenho de Bezerros Holandeses para Produção de Vitelos

O experimento foi realizado com 20 bezerros holandeses, todos machos não castrados, com 75 dias de idade e peso vivo médio de 76 kg, com o objetivo de avaliar o desempenho e a viabilidade econômica de produzir vitelos. Os animais foram alimentados com dietas contendo 45, 60, 75 e 90% de concentrado. As dietas foram constituídas de feno de capim-coastcross, fubá de milho, farelo de soja e mistura mineral. O delineamento experimental foi em blocos casualizados, com quatro tratamentos e cinco blocos. Antes do início do experimento, todos os animais foram submetidos a um mesmo sistema de aleitamento. O período experimental foi variável para cada tratamento, em que os animais eram abatidos à medida que atingiam o peso médio de 200 kg. As análises de variância para consumo de matéria seca, consumo de proteína bruta e conversão alimentar da matéria seca mostraram não haver efeito significativo dos níveis de concentrado nas dietas. Todavia, as análises de regressão mostraram efeito linear decrescente, com o aumento do nível de concentrado, para o consumo de fibra em detergente neutro, e aumento linear para o ganho de peso diário, proporcionando redução de 35 dias no confinamento para os animais alimentados com dietas contendo 90% de concentrado. Efeitos significativos devido ao nível de concentrado também foram verificados na conversão alimentar da fibra detergente neutro e da proteína bruta, sendo que a melhora da eficiência alimentar ocorreu com o acréscimo de concentrado na dieta. Os custos de produção indicaram a viabilidade de produzir vitelos utilizando bezerros holandeses.

Tamanho de Órgãos e Vísceras de Bezerros Holandeses, para Produção de Vitelos, Recebendo Dietas com Diferentes Níveis de Concentrado

O experimento foi realizado com 20 bezerros holandeses puros por cruza, todos machos não castrados, com 75 dias de idade e peso médio de 76 kg, submetidos ao mesmo sistema de aleitamento antes do experimento. O objetivo foi avaliar o tamanho relativo dos órgãos internos e vísceras dos animais alimentados com dietas contendo 45, 60, 75 e 90% de concentrado. As dietas foram constituídas de feno de coastcross, fubá de milho, farelo de soja e mistura mineral, fornecidas à vontade. O delineamento experimental foi em blocos casualizados, com quatro tratamentos e cinco repetições. O período experimental foi variável para cada tratamento, em que os animais foram abatidos à medida que atingiram o peso vivo médio de 200 kg e, antes do abate, foram submetidos a jejum de 16 horas. À medida que se aumentaram os níveis de concentrado nas dietas, os pesos absolutos do fígado, rins, pulmões, abomaso, mesentério e a gordura presentes nas carcaças aumentaram linearmente. Não houve diferença significativa para o peso dos demais órgãos e vísceras, assim como para as partes não constituintes das carcaças como couro, patas, cabeça e cauda, em relação aos níveis de concentrado estudados.

Nível de proteína bruta para bezerros de corte desmamados aos 66 dias de idade

O objetivo deste trabalho foi avaliar o consumo médio diário de matéria seca (CMS), CMS por 100 kg de peso vivo (CMSP), CMS por unidade de peso metabólico (CMSM), a conversão alimentar (CA) e o ganho de peso médio diário (GMD) de bezerros de corte, alimentados com diferentes níveis de proteína bruta (PB) na dieta. Foram utilizados 47 bezerros inteiros, da raça Braford, desmamados aos 66 dias de idade com peso médio de 76,4 kg. Os animais foram alimentados à vontade com silagem de aveia e concentrado (50/50), com níveis de 13, 15, 17 e 19% de PB na dieta total. O período de adaptação ao alimento e manejo foi de 21 dias. Os animais foram pesados com jejum de sólidos de 14 horas, a intervalos regulares de 21 dias durante o período experimental de 84 dias. Verificou-se, por meio da análise de regressão linear e múltipla, que não ocorreram efeitos significativos relacionando o CMS, CMSP, CMSM, CA e GMD e o nível de PB na dieta. Observou-se que CMS, CMSP e CMSM aumentaram linearmente com o avanço do período experimental, demonstrando o aumento da capacidade de ingestão com o aumento do peso vivo. Os valores de GMD obtidos foram de 644; 701; 693 e 730 g/dia para os níveis de 13; 15; 17 e 19% de PB na dieta, respectivamente. Os ganhos de peso foram superiores àqueles normalmente atingidos ao pé da vaca em condições de campo nativo ou desmamados precocemente e mantidos em pastagem cultivada.

Implant sequence effects in intact male Holstein veal calves: carcass characteristics.

Seven sequences of growth promotant implants were used in intact male Holstein veal calves (n = 443). Implants were administered on d 0 (within 4 d after arrival at the veal barn), 42, and 84. The implants used were placebo (0), Z (36 mg zeranol), ET (20 mg estradiol, 200 mg testosterone), EP/2 (10 mg estradiol, 100 mg progesterone), EP (20 mg estradiol, 200 mg progesterone), and EBA (24 mg estradiol, 120 mg trenbolone acetate). The following sequences were compared: 0-0-0 (negative control), 0-ET-ET, Z-ET-ET, 0-EP-EP, Z-EP-EP, 0-EP/2-EBA, and Z-0-EBA. Sequences 0-EP-EP, Z-EP-EP, and 0-EP/2-EBA increased (P<.05) carcass weight from 3.3 to 3.9% compared to nonimplanted controls. There were no differences (P>.05) in percentage of carcass weight accounted for by the fore vs. rear halves of carcasses, suggesting there was no difference in the distribution of weight. Although there were differences in longissimus area, the results were not consistent, except that there was a trend for longissimus area to be increased by the use of estrogenic-androgenic implants (ET and EBA). There were no differences among implant sequences for carcass conformation, fat cover, muscle texture, marbling/ feathering, muscle color, or muscle chemical composition. Of four implant sequences (0-0-0, 0-ET-ET, 0-EP-EP, and 0-EP/2-EBA) tested for differences in Warner-Bratzler shear force tenderness, the latter two sequences averaged higher (P<.05) for shear force than did the negative control. These results suggest that aggressive implant strategies in young, intact Holstein bull calves (raised as veal) have minimal effects on carcass characteristics.

Implant sequence effects in intact male Holstein veal calves: live and slaughter traits.

Seven sequences of growth promotant implants were used in special-fed intact male Holstein veal calves (n = 443). Calves received implants 4 d after arrival at the veal barn, 42, and 84. The following implants were used: placebo (0), Z (36 mg zeranol), ET (20 mg estradiol, 200 mg testosterone), EP/2 (10 mg estradiol, 100 mg progesterone), EP (20 mg estradiol, 200 mg progesterone), and EBA (24 mg estradiol, 120 mg trenbolone acetate). The following sequences were compared: 0-0-0 (negative control), 0-ET-ET, Z-ET-ET, 0-EP-EP, Z-EP-EP, 0-EP/2-EBA, and Z-0-EBA. From 0 to 42 d, Z implants increased (P<.05) ADG by 3.4% compared to placebo. However, implant schemes without an initial Z implant (0-ET-ET and 0-EP-EP) had higher (P<.05) mean ADG for the period from d 42 to 84. From 84 d to the end of the experiment, only the 0-EP/2-EBA treatment increased (P<.05) ADG compared to 0-0-0. Over the entire trial 0-ET-ET, 0-EP-EP, Z-EP-EP, and 0-EP/2-EBA implant sequences increased (P<.05) ADG by 3.2, 3.2, 2.4, and 4.7%, respectively, compared to the 0-0-0 sequence. Blood traits measured within 2 wk before slaughter were not affected by implant sequence, except that sequences with EP had higher (P<.05) leukocyte counts than were observed for the other sequences. Testicular weight was less (P<.01) for all of the implant sequences than for the negative control and less (P<.05) for Z-ET-ET than for 0-ET-ET, 0-EP-EP, 0-EP/2-EBA, and Z-0-EBA. The type and frequency of medical treatments did not differ among implant sequences for any of the 42-d phases, or over the entire trial. Generally, the growth promotant implants currently approved for beef cattle resulted in approximately 50% of the increase in growth rate in Holstein intact bull calves, as has been observed in beef-type steers or heifers.

The effects of long-term administration of recombinant bovine somatotropin (Posilac) and Synovex on performance, plasma hormone and amino acid concentration, and muscle and subcutaneous fat fatty acid composition in Holstein-Friesian bull calves.

The effect of recombinant somatotropin (rbST), Synovex (Syn), and their combination (rbST+Syn) on intact male calves was examined in an experiment that lasted an average of 238 d. Holstein-Friesian bull calves were allotted to one of four subtreatments (n = 14/treatment) in a factorial arrangement. There were two levels of rbST (0; rbST) and two levels of the estrogenic growth promoter Synovex (0; Syn). The rbST was administered once every 2 wk as injections of 500 mg of Posilac. Synovex (C and S) was implanted at 90-d intervals. The animals were fed for ad libitum consumption a diet with a metabolizable energy concentration of 11.7 MJ/kg DM and 15% crude protein. The hot carcasses were weighed after the removal of kidney, pelvic, and cod fats, which were weighed separately. The 12th rib cut was saved for analysis. Average daily gain and feed conversion efficiency were increased by rbST treatment by 9% (P < .005) and 10% (P < .016), respectively. There was no significant effect of Syn treatment, nor was there a rbST x Syn interaction. The proportion of the fat of the large depots in the carcass was reduced by 34% (P < .0001) and in the longissimus muscle by 32% (P < .16) owing to the rbST treatment. The plasma concentrations of GH, insulin, and thyroxin were increased by rbST treatment (P < .001, P < .01, and P < .03, respectively). The concentration of IGF-I was not affected. Synovex had no effect on plasma hormone concentration. Plasma essential and nonessential amino acid concentrations were reduced by 14 and 9%, respectively, when rbST was injected. Concentrations of cholesterol and fatty acids in muscle and subcutaneous fat were not affected (P > .072) by the rbST treatment. Synovex increased the monounsaturated fatty acids (MUFA), and the combinaton of Syn with rbST reduced polyunsaturated fatty acid (PUFA) concentration in the longissimus muscle (at the 12th rib). The reduced muscle fat content of the rbST-treated animals was associated with a trend toward an increase in polyunsaturated fatty acids.

Effect of a Single Intravenous Injection of N‐Methyl‐D,L‐Aspartic Acid on Secretion of Luteinizing Hormone and Growth Hormone in Holstein Bull Calves

The role of N-methyl-D-aspartate (NMDA) receptor activation in the central regulation of luteinizing hormone (LH) and growth hormone (GH) was tested by administering a bolus intravenous dose of N-methyl-D,L-aspartic acid (NMA), a NMDA receptor agonist, to 24-week-old intact (n=5), estradiol-treated intact (n=3) and castrated (n=3) Holstein bull calves. The calves were bled for 12h pre- and 100 min post-NMA injection (1.75 mg-/kgBW) periods at 10 min intervals. Concentrations of LH and GH in plasma were measured by specific RIA. Prior to administration of NMA, the average concentration of LH, but not GH, differed significantly among the 3 groups. As expected, administration of estradiol prevented the normal ontogeny of pulsatile LH secretion, while castration resulted in an increased frequency of LH discharges. Injection of NMA resulted in an acute (P<0.001) release of LH in 3 of 5 intact and 3 of 3 estradiol-treated intact calves with the peak response being observed at 20 min (3.18 +/- 1.3 and 5.58 +/- 1.3 ng/ml, respectively) following the challenge. Treatment with NMA did not alter the release of LH in castrate calves. Concentrations of GH in plasma increased (P<0.001) within 20 to 30 min after administration of NMA in intact, estradiol-treated intact and castrate calves with a similar response being observed in each group. Based on these findings, we suggest an involvement of glutamatergic neurotransmission in the hypothalamic or supra-hypothalamic control of LH and GH secretion, and that the excitatory effects of NMDA receptor activation on LH release are overtly influenced by gonadal steroids in bull calves.