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1.
Breed susceptibility to nematode infection was evaluated in Angus (Bos taurus) and Brangus (B. indicus crossbreed) cattle. A cow-calf herd and a yearling replacement heifer herd were monitored during one grazing season. Calves were born in March and were weaned in October. Individual rectal fecal samples were collected monthly from the two herds and processed for fecal egg counts (FEC) and coprocultures. Cow and calf FEC increased from April, reaching maximum values during the summer. Angus cows and calves had significantly (p<0.05) greater FEC than Brangus cows and calves, and Haemonchus and Cooperia were the predominant genera. Replacement heifer FEC showed a similar pattern with maximum levels during late summer/fall, and Haemonchus was the predominant genus. No significant differences were seen between breeds, however, infection levels were consistently lower in Brangus heifers. Ostertagia was present in cows and heifers only in fall/winter, which is consistent with summer inhibition. The data suggested that cows were an important source of pasture contamination for their susceptible calves and that the Brangus breed was relatively more resistant to infection. The use of B. indicus crossbreeds may help in alleviating reliance on chemical control by reducing the rate of pasture contamination and subsequent infection losses.  相似文献   

2.
A study was conducted to compare Brangus, Beefmaster, Gelbray, and Simbrah breed influences for economically important traits. Brangus (9), Beefmaster (12), Gelbray (10), and Simbrah (7) sires were used in purebred and crossbred (Brahman x Hereford F1 cows) matings to generate calves (326) in eight breed groups. Beefmaster cows were of similar size (448 kg), Brangus and Gelbray cows were 11% heavier (501 and 503 kg), and Simbrah cows were 21% heavier (548 kg) compared to Brahman x Hereford F1 cows (452 kg). Calves sired by Brangus and Beefmaster bulls had lower birth weights (35 vs 38 kg; P < 0.05), preweaning growth rates (0.87 vs 0.91 kg x d(-1); P < 0.01), and weaning weights (206 vs 219 kg; P < 0.01) than Gelbray- and Simbrah-sired calves. Birth weights, preweaning ADG, and weaning weight and hip heights were similar between Brangus- and Beefmaster-sired calves. Simbrah-sired calves had greater preweaning growth rates (0.94 vs 0.88 kg x d(-1); P < 0.05), weaning weights (227 vs 211 kg; P < 0.01), and adjusted 205-d hip heights (126 vs 122 cm; P < 0.05) than Gelbray-sired calves. Straightbred Angus steers were introduced in the postweaning portion of the study. Steer calves were placed on feed at an average age of 14.5 mo. Steers were removed from the feedlot upon attaining a targeted 10 mm of backfat. Feedlot ADG did not differ among sire breeds. Brahman-derivative sired steers required an additional 54 d on feed (P < 0.01) and were 86 kg heavier (P < 0.01) at harvest than Angus steers. Continental-Brahman steers spent an additional 25 d on feed (P < 0.05) and were 35 kg heavier (P < 0.01) at harvest than British-Brahman steers. Simbrah-sired steers were 52 kg heavier (P < 0.01) at harvest than Gelbray-sired steers when fed for a similar number of days (211 vs 203 d). However, straightbred Simbrah steers required an additional 12 d on feed (P < 0.01) and weighed 47 kg more (P < 0.01) than Simbrah-sired crossbred steers. The economic value of the heavier calf weaning weights may be offset by the attendant larger cow size of the Continental-Brahman compared to the British-Brahman breeds. Similarly, the heavier weights of Continental-Brahman compared to British-Brahman steers, when harvested at a prescribed level of fatness may be viewed as a benefit, but the increased number of requisite days in the feedlot is a disadvantage.  相似文献   

3.
Hair samples from newborn heifer calves on Holstein dairy farms in southwestern Ontario were analyzed for selenium content by means of instrumental neutron activation analysis. The mean selenium level in the hair of calves which subsequently died at less than six weeks of age did not differ from selenium levels in the hair of calves matched by farm and birthday (overall mean 0.28 ppm). The mean selenium level in the hair of calves which were not treated for disease during the first four weeks of life was 0.42 ppm, while that from appropriately matched treated calves was 0.36 ppm; the difference between the means was significant at p = 0.054. Based on the above associations, it is suggested that higher selenium levels in newborn calves may have some protective effect against morbidity.  相似文献   

4.
Indicators of immune-mediated disease were studied in calves with severe natural bovine respiratory syncytial virus infection. Although antigen and antibody were detected concurrently in most calves, immune complexes were not detected by use of immunofluorescence, ELISA, and binding of the 1q component of complement. Complement component C3, however, was observed by immunofluorescence in the cranioventral, virus-infected portion of the lungs of 19 of 25 calves. Reductions in the amount of histamine and in the numbers of mast cells and mast cell granules in the virus-positive cranioventral and virus-negative caudodorsal portions of the lungs, indicated activation of mast cells and liberation of their granule contents. On the basis of these and previous findings, a model for the pathogenesis of bovine respiratory syncytial virus-induced disease was proposed.  相似文献   

5.
The efficacy of a treatment schedule using ivermectin, given subcutaneously at the rate of 200 micrograms kg-1, to control gastrointestinal parasitism and its effect on liveweight gains was assessed. Two herds with a total of 466 Hereford X Brangus cow/calf pairs were used. Each herd was on six pasture plots of comparable size, stocking rate, and quality and quantity of forage. Pasture groups were paired across the two herds. Pasture groups from one herd were randomly assigned to nonmedicated control and the other three to ivermectin treatment. Treatment assignments per pasture group were reversed in the other herd. The control group contained 118 cows and 112 calves and the medicated group 121 cows and 115 calves. Cows were treated in early July and the calves in late July or early August. Cattle from one herd were weighed on Days -28, 0 (day of cow treatment), 30 (day of calf treatment), 58, and 86, while the other herd was weighed on Days -29, 0 (day of cow treatment), 27 (day of calf treatment), 61, and 89. Day 0 was not the same calendar day for the two herds. Fecal samples for parasite egg counts were obtained from the rectum on weight days from five cows and six calves from each pasture; in most cases the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves between day of treatment for cows and the end of the trial.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
The lower respiratory tract of six 8-day-old calves and six adult cows was fixed in either isotonic formal-acetic-acid or neutral buffered formalin in order to study the morphology, density and distribution of mast cells. They were found at all levels of the tract with the highest density in the major bronchi. Tissues from cows had significantly more mast cells than those from calves. There were significantly more mast cells detected in calf airways fixed with isotonic formal-acetic-acid compared with those seen in the same tissues fixed with neutral buffered formalin. Regardless of the age and fixation, mast cells were located predominantly in the alveolar septa and in the lamina propria of airways. They were also commonly encountered within the mucosal epithelium of the trachea. Ultrastructurally, mast cells in bovine airways and lung contained two types of intracytoplasmic granules as described in other species.  相似文献   

7.
Dairy cattle suffer stress from management and production; contemporary farming tries to improve animal welfare and reduce stress. Therefore, the assessment of long-term hypothalamic-pituitary-adrenal function using non-invasive techniques is useful. The aims in this study were: to measure cortisol concentration in cow and calves hair by radioimmunoassay (RIA), to test cortisol accumulation in bovine hair after adrenocorticotropic hormone (ACTH) challenges, and determine the influence of hair color on cortisol concentrations. Fifteen Holstein heifers were allotted to 3 groups (n = 5 each): in control group (C), just the hair was sampled; in the saline solution group (SS), IV saline solution was administered on days 0, 7, and 14; and the ACTH group was challenged 3 times with ACTH (0.15 UI per kg of body weight) on days 0, 7, and 14. Serum samples from the SS and ACTH groups were obtained 0, 60 and 90 min post-injection. Serum cortisol concentration was greater 60 and 90 min after injection with ACTH. Hair was clipped on days 0, 14, 28, and 44. Hair cortisol was methanol extracted and measured by RIA. Hair cortisol was preserved for 11 mo. Hair cortisol concentrations in the ACTH group were greater than in the saline and control groups on days 14 and 28, but not on day 44. Concentrations were greater in calves than in cows and greater in white hair than in black hair. Cortisol accumulated in bovine hair after ACTH challenges, but the concentration was affected by both age and hair color. If hair color effects are taken into account, assessing cortisol concentration in hair is a potentially useful non-invasive method for assessing stress in cattle.  相似文献   

8.
Angus Plus cattle offer advantages for heat tolerance and forage utilization by introduction of Brangus and Brahman to Angus. To evaluate its adaptability in Hawaii Islands, we reported the growth performances of 213 F1 Angus Plus calve grazing on pasture. Least-square means of pre-weaning ADG ranged from 1,087 to 1,167 g in bull calves and from 1,030 to 1,048 g in heifer calves. The 205 d-adjusted weaning weight were 226 to 285 kg in bulls and 214 to 252 kg in heifers. The birth weight and hip height at birth were significantly correlated with weaning weight, 205 d-adjusted weaning weight, hip height at weaning and pre-weaning ADG (P < 0.01). Sire group significantly influenced pre-weaning growth performances through interaction with sex of calf. Bull calves from sire group of high growth were 1.0–3.8 kg heavier in birth weight than the bull calves from other sires (P < 0.001). Sire group x sex interaction was significant (P < 0.05) for calf birth weight, 205-d adjusted weaning weight and pre-weaning ADG. Sire group also played a significant role in hip height at birth (P < 0.05). Selections of the sires preferable for growth significantly improved calf pre-weaning growth performances.  相似文献   

9.
Data in this experiment consisted of 418 lactation records, and weaning and birth weight records from 600 crossbred calves. The traits evaluated included birth weight, weaning weight, weaning weight per cow exposed, weaning weight per weight of cow, weaning weight per weight of cow exposed, and predicted milk yield. Angus, Brangus, and Gelbvieh sires were mated to purebred Hereford cows. Yearling and 2-yr-old Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters then were bred to Polled Hereford bulls (Data Set 2). Later-parity Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters were mated to Salers or Simmental sires (Data Set 3). Differences between Gelbvieh- and Brangus-sired calves or Gelbvieh-Hereford and Brangus-Hereford daughters were never significant for weaning weight, birth weight, or milk yield. Angus crosses had the lowest weaning weight, birth weight, and milk yield, but the highest kilograms of calf weaned per cow exposed in all data sets. Angus-Hereford and Brangus-Hereford dams had higher weaning weight per weight of cow exposed than Gelbvieh-Hereford dams (P < .01) in Data Set 3. There were no other significant differences related to cow weight.  相似文献   

10.
Reliable genomic prediction of breeding values for quantitative traits requires the availability of sufficient number of animals with genotypes and phenotypes in the training set. As of 31 October 2016, there were 3,797 Brangus animals with genotypes and phenotypes. These Brangus animals were genotyped using different commercial SNP chips. Of them, the largest group consisted of 1,535 animals genotyped by the GGP‐LDV4 SNP chip. The remaining 2,262 genotypes were imputed to the SNP content of the GGP‐LDV4 chip, so that the number of animals available for training the genomic prediction models was more than doubled. The present study showed that the pooling of animals with both original or imputed 40K SNP genotypes substantially increased genomic prediction accuracies on the ten traits. By supplementing imputed genotypes, the relative gains in genomic prediction accuracies on estimated breeding values (EBV) were from 12.60% to 31.27%, and the relative gain in genomic prediction accuracies on de‐regressed EBV was slightly small (i.e. 0.87%–18.75%). The present study also compared the performance of five genomic prediction models and two cross‐validation methods. The five genomic models predicted EBV and de‐regressed EBV of the ten traits similarly well. Of the two cross‐validation methods, leave‐one‐out cross‐validation maximized the number of animals at the stage of training for genomic prediction. Genomic prediction accuracy (GPA) on the ten quantitative traits was validated in 1,106 newly genotyped Brangus animals based on the SNP effects estimated in the previous set of 3,797 Brangus animals, and they were slightly lower than GPA in the original data. The present study was the first to leverage currently available genotype and phenotype resources in order to harness genomic prediction in Brangus beef cattle.  相似文献   

11.
乌连颗粒剂对细菌性犊牛腹泻的临床疗效观察   总被引：1，自引：0，他引：1  
根据细菌性犊牛腹泻的临床诊断标准,选取典型阳性病例1 18头,用于观察乌连颗粒剂对犊牛腹泻的疗效作用。结果表明,乌连颗粒剂高剂量组（75g/kg体重）、中剂量组（50g/kg体重）、低剂量组（25g/kg体重）及环丙沙星注射液对照组（1mL/kg体重）对细菌性犊牛腹泻的治疗有效率分别为92.30%、82.12%、73.68%、88.89%,与阳性对照组（不给药）均差异极显著（P〈0.01）;治愈率分别为88.46%、75.00%、63.15%、81.48%。说明乌连颗粒剂对细菌性犊牛腹泻具有良好的治疗效果。  相似文献   

12.
Oxytropis sericea and Astragulus mollissimus (commonly referred to as locoweeds) are responsible for significant monetary losses annually to producers in the western United States. Therefore, a study was conducted over 2 yr to evaluate the influence of beef breeds (Brangus, Charolais, and Hereford) on locoweed consumption. Twenty-one steers (seven per breed group) were used initially in each year of the study on pastures located near Sofia, NM in yr 1 and on pastures located near Des Moines, NM in yr 2. Steers were placed in separate pastures for each breed (3 pastures/yr) and were rotated through pastures on a weekly basis. Number of bites taken of cool and warm season grasses, forbs, and locoweed were recorded daily for each steer. Blood samples were collected on d 0, 7, 21, and 28 for determination of serum alkaline phosphatase. A breed x year interaction (P < 0.10) was observed for locoweed consumption. During yr 1, Brangus cattle consumed more locoweed during wk 1 of the study than Charolais or Herefords (12, 2, and 3% of bites recorded for Brangus, Charolais, and Hereford, respectively). During yr 2, Brangus cattle consumed more (P < 0.10) locoweed during wk 1 (15, 2, and 0%), wk 2 (6, 1, and 1%), and wk 3 (9, 4, and 0% for Brangus, Charolais, and Hereford, respectively) of the experiment compared with Charolais and Hereford cattle. No differences were noted among breeds for serum alkaline phosphatase (AP) concentrations during yr 1. Serum AP was increased (P < 0.01) for Brangus versus Charolais and Hereford on d 7 and 14 during yr 2. Results suggest that differences among breeds exist for locoweed consumption.  相似文献   

13.
Understanding mechanisms that regulate growth and reproduction are important for improving selection strategies in cattle. In this study, Angus, Brangus, and Brahman bulls (n = 7 per breed) of similar age were selected from a group of 65 weanlings. Bulls were evaluated after weaning (i.e., approximately 6 mo of age) for 112 d for serum concentrations of metabolic hormones and glucose, growth, and reproductive traits. Performance data and blood sera were collected on d 0, 28, 56, 84, and 112. Sera were also collected in periods from d 50 to 59 (56D) and 103 to 112 (112D). Angus bulls were heavier (P < 0.05) throughout the study than Brahman bulls and were heavier than Brangus bulls on d 56, 84, and 112. Initial and final BW for Angus, Brangus, and Brahman bulls were 292.7, 260.6, and 230.4 and 468.3, 435.6, and 350.7 +/- 12 kg, respectively. Conversely, Brahman bulls had greater hip height (P < 0.05) than Brangus, and Brangus were taller (P < 0.05) than Angus. Angus bulls had the greatest (P < 0.05) scrotal circumference (SC) and Brahman bulls the least. Mean SC across days was 31.5, 29.7, and 25.0 +/- 0.6 cm for the three respective breeds. Serum testosterone was greater (P < 0.01) in Angus and Brangus bulls (10.0 and 8.9 +/- 1.4 ng/mL) than in Brahman bulls (4.0 +/- 1.4 ng/mL) throughout the study. After d 112, 100, 86, and 57% of the Angus, Brangus, and Brahman bulls passed a breeding soundness exam (P = 0.51). Serum concentrations of IGF-I and leptin were greater (P < or = 0.06) in Angus bulls on d 56, 84, and 112 than in Brangus and Brahman bulls. Serum concentrations of GH (P < 0.08) and glucose (P < 0.03) were greater in Brangus bulls than in Angus or Brahman bulls throughout the study. Prediction analyses suggested that serum concentrations of leptin could be used to predict (P < or = 0.08) BW and SC (R2 > 0.82) in the 56D and 112D periods among these breeds. Leptin was also useful in predicting (P < or = 0.09) serum concentrations of GH and testosterone in the 112D period (R2 > 0.32). Residual correlation analyses with the effect of breed removed suggested that leptin was correlated (r > or => 0.53, P < 0.05) with both SC and serum testosterone. Angus and Brahman cattle differ in phenotype, level of adiposity, and rate of sexual development. Data herein suggest that these characteristics could be due to varying mechanisms by which metabolic hormones such as leptin, GH, and(or) IGF-I are regulated.  相似文献   

14.
Lactoferrin (LF) is a cationic iron-binding glycoprotein that is abundantly expressed and secreted from glandular epithelial cells and a prominent component of the secondary granules of polymorphonuclear neutrophils. Various in vitro and in vivo experiments demonstrate anti-microbial, -viral, -mycotic and -inflammatory effects of LF, associated with modulations of the immune system. Effects of oral administered LF on selected immune system parameters were studied in calves. Five calves were fed LF beginning on day 3 of life with colostral milk and starting on day 6 of life milk replacer enriched with 0.16% LF was fed. The average daily intake of LF per calf was 1.5-1.6 g/day. Additional five calves served as control group with identical treatment except for the LF supplementation. At the end of the study (day 61 of life), all calves were slaughtered and various tissues were sampled for histological and gene-expression studies. LF given orally was shown to act as an immunomodulatory agent by enhancing the size of Peyer's patches in the ileum and increasing blood serum immunoglobulin G levels. In addition, the number of peripheral blood leucocytes increased and mRNA levels of various interleukins (IL) such as IL-1beta, IL-8, IL-10 and interferon gamma (IFNgamma) in those cells in response to LF treatment were enhanced. In blood, the mRNA expression of the pro-inflammatory marker genes IL-1beta and IFNgamma decreased over 10-week treatment. Additionally, LF feeding decreased villus sizes in the jejunum. Together these findings emphasize the ability of LF to stimulate prominent immune system parameters and that it has the capacity to modulate the immune responses in a positive way.  相似文献   

15.
Field data records on 10,511 Hereford and 2,522 Brangus bulls between 330 and 430 d of age were analyzed to find age of calf and age of dam adjustment factors for yearling scrotal circumference. Age of calf adjustment factors were .024 cm/d for Hereford bulls and .041 cm/d for Brangus bulls. Sons of Hereford dams were adjusted to a 6- to 8-yr dam age basis by adding .7, .3, .2, .2 or .3 cm for dams 2, 3, 4, 5 or 8 or more years old, respectively. Age of dam adjustment factors for Brangus bulls were .8, .4, .3 and .2 for dams 2, 3, 4 or 8 or more years old, respectively. Variance and covariance components for yearling scrotal circumference and several growth traits were estimated within breed using multiple-trait models and pseudo expectations involving the solutions and the right-hand sides of the mixed-model equations. Additive heritability estimates for yearling scrotal circumference of .53 and .16 were found for Hereford and Brangus bulls, respectively. Maternal heritability estimates of .12 and .10 were found for Hereford and Brangus bulls, respectively. Genetic correlations between yearling scrotal circumference and other growth traits were positive for both sets of data indicating that selection for yearling scrotal circumference should not adversely affect other growth traits in either breed. Environmental correlation estimates between yearling scrotal circumference and adjusted birth weight and between yearling scrotal circumference and adjusted 205-d weight and adjusted 365-d height were positive and moderate in magnitude for both breeds.  相似文献   

16.
The effect of growth and parturition on hair cortisol concentrations of cattle was investigated. Plasma, saliva, and hair (black and white from the shoulders and hip) samples were collected from calves at 6 and 24 weeks old and from dairy cattle at the dry (1 and 2 months prepartum) and lactation (10, 50, 150, and 250 days postpartum) periods. Plasma and saliva cortisol concentrations were lower in 24-week-old calves than those of 6-week-old calves, and hair cortisol concentrations decreased regardless of color and position. In 6-week-old calves, hair cortisol concentrations differed between sampling positions, but this difference was not observed in 24-week-old calves. Plasma and saliva cortisol concentrations increased before parturition until 10 days postpartum then decreased until 50 days postpartum. The same trend was observed in the cortisol concentrations of white hair. Contrarily, cortisol concentrations in black hair remained unchanged and was lower than that in white hair. Hair cortisol concentration can vary greatly depending on the location on the body, hair color, cattle age, or parturition. When this method is used, all of the above factors must be considered.  相似文献   

17.
This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) to beef calves at weaning on their performance, physiological responses, and behavior during a 42-d preconditioning program. Eighty calves (40 heifers and 40 steers; 90% British × 10% Nellore) were weaned at 233 ± 2 d of age (day 0); ranked by sex, weaning age, and body weight (BW); and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 40) or placebo (diethylene glycol monoethyl ether; CON; n = 40). Treatments (5 mL) were topically applied to the nuchal skin area of each animal following dam separation. Within treatment, calves were allocated to one of eight drylot pens (four pens per treatment; pen being the experimental unit) and received a free-choice total mixed ration (TMR) from day 0 to 42, intake of which was assessed daily. Live behavior observations were conducted on days 1, 2, 4, 8, 16, and 32. Temperament was assessed and blood samples were collected via jugular venipuncture on days −21, 0, 3, 7, 14, 28, and 42. Hair samples were collected from the tail switch on days 0, 14, 28, and 42. Calves were vaccinated against bovine respiratory disease viruses on days −21 and 0. Average daily gain from day 0 to 42 did not differ between treatments (P = 0.57) but was greater (P = 0.05) in BAS vs. CON calves from day 0 to 28. Intake of TMR was greater (P = 0.05) during the first week for BAS vs. CON calves (treatment × week; P = 0.08). The mean proportion of calves feeding simultaneously and performance of social and play behaviors were greater (P ≤ 0.05) for BAS vs. CON calves. Escape attempts were greater (P < 0.01) for BAS vs. CON calves on day 1 (treatment × day; P = 0.03). Exit velocity was greater (P = 0.04) for CON vs. BAS calves on day 14 and tended (P = 0.10) to be greater for CON vs. BAS calves on day 7 (treatment × day; P = 0.03). Mean plasma concentrations of haptoglobin were greater (P = 0.02) in CON vs. BAS calves. Hair cortisol concentrations were greater (P = 0.05) in CON vs. BAS calves on day 14 (treatment × day; P = 0.03). Mean serum concentrations of antibodies against bovine viral diarrhea virus were greater (P = 0.02) in BAS vs. CON calves. Collectively, BAS administration to beef calves at weaning alleviated stress-induced physiological reactions, improved temperament evaluated via chute exit velocity, enhanced humoral immunity acquired from vaccination, and appeared to have accelerated adaptation to novel management scheme and environment.  相似文献   

18.
In a 3-year-old Holstein cow, a tumor mass replaced the left olfactory bulb. The tumor was highly or moderately cellular, and consisted of tumor cells showing pleomorphism and anaplasia, sometimes with intracytoplasmic granules. The tumor showed weak reactivity for neurofilaments (NF) in most cells with distinct staining in a minority, and it was extremely rare to see neoplastic cells with positivity for glial fibrillary acidic protein (GFAP). The neoplastic cells displayed some ultrastructural features reminiscent of ganglionic cells, and the cytoplasmic granularity was due to the presence of numerous lysosomes. This tumor expressing both NF and GFAP may be histogenetically related to brain tumors of pluripotential cell origin in calves.  相似文献   

19.
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20.
Calves were dosed with 50 g of copper oxide granules orally or given 120 mg copper glycinate subcutaneously. There was no significant difference between the weights of calves given either treatment during the trial. However, the copper oxide treatment resulted in sustained higher concentration of plasma copper and higher liver reserves than the glycinate treatment.  相似文献   

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