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Digestion and performance responses to lasalocid and concentrate supplements by beef cattle fed bermudagrass hay.

Beef cattle consuming bermudagrass hay were not supplemented or received a limited amount of ground corn alone or with a mix of protein meals to determine influences of concentrate supplementation on digestion and performance when the ionophore lasalocid (200 mg daily) was given. With limited feed intake, supplement treatment did not change the acetate to propionate shift in beef cows occurring with lasalocid (P < 0.06). Lasalocid did not affect sites of digestion of organic matter or nitrogen with any supplement treatment. However, lasalocid decreased (P < 0.10) ruminal digestion of neutral and acid detergent fibre. Live-weight gain by growing beef calves ingesting bermudagrass hay ad libitum was higher (P < 0.05) with than without supplementation and tended (P < 0.12) to be greater for corn plus protein meals than for corn alone. Lasalocid did not affect or interact with supplement treatment in feed intake or live-weight gain of heifers (236 kg; no growth stimulant) or steers (237 kg; treated with 200 mg progesterone and 20 mg estradiol benzoate). Lasalocid at 200 mg daily did not improve digestion characteristics or influence performance by beef cattle consuming a Basal diet of bermudagrass hay. Further, effects of lasalocid were not modulated by supplementation with concentrate, concentrate type or sex or growth stimulant usage.

Animal Feed

Xylazine-induced hyperglycemia in beef cattle.

Intravenous administration of xylazine to beef cattle (10 animals, 0.2 mg/kg of body weight) resulted in rapid onset (less than 15 minutes) of hyperglycemia. Plasma glucose values increased to 195 +/- 15 mg/dl and 305 +/- 10 mg/dl at 15 minutes and 3 hours, respectively. Concomitantly, plasma insulin concentrations dropped from 23 +/- 2 microU/ml before xylazine to 5.8 +/- 0.7 microU/ml and 2.4 +/- 0.3 microU/ml at 15 minutes and 3 hours, respectively. Parallel decreases (20%) were observed for percentage of hemoglobin, red blood cell number, and packed cell volume. Plasma urea nitrogen was significantly (P less than 0.01) incrased within 3 hours of xylazine administration (6.7 +/- 0.9 mg/dl vs 11.4 +/- 0.7 mg/dl). Marked changes in concentrations of plasma-free fatty acids were not observed. Alternative means of anesthesia must be considered in those instances in which biopsy material is to be used for studies of carbohydrate metabolism in vitro.

Animals

Synchronisation of oestrus in beef cattle artificial breeding programs using prostaglandin F2alpha.

PGF2alpha either as a subcutaneous injection (8 or 10mg) or intrauterine infusion (dose 5 mg) successfully synchronised oestrus in beef cattle AI programs. The beef cattle programs were managed by 1 of the following 2 systems. 1. Two 10-day insemination periods, 1 for the first and the second for the repeat inseminations. Oestrus was detected and oestrus cows inseminated for the first 4 days of the first period. On the fifth day all cows not inseminated were treated with PGF2alpha. The treated cattle came into oestrus and were inseminated over the following 2 to 5 days. 2. Two PGF2alpha treatments 10 days appart followed by two 4-day insemination perids. During the first 4-day period, cows exhibiting synchronised oestrus were inseminated. Cows returning to oestrus were inseminated during the second 4-day period, about 18 days after the first, period. Synchronisation of oestrus was not sharp, oestrus being distributed over 7 days, with the majority of cows being in oestrus on the third (42.3%) and fourth (22.4%) days. The route of administration of PGF2alpha (injection or infusion) did not effect oestrus synchronisation. PGF2alpha by either route of administration did not effect the fertility of cows inseminated at either the synchronised or subsequent oestrus. Pregnancy rates at the synchronised oestrus were higher when cows were inseminated after dectection of oestrus than when they were inseminated without reference to oestrus at a fixed time 3 days after PGF2alpha treatment (mass injection). Oestrus synchronisation greatly reduced the input of time, labour and feed required during the total program. However, oestrus synchronisation did not alter the overall efficiency of artificial breeding programs measured in terms of the proportion of cattle entering a program that were inseminated and became pregnant. The main problem encountered was drug wastage through unknowingly treating cows and heifers that were not cycling.

Animals

Circulating placental lactogen levels in dairy and beef cattle.

Levels of bovine placental lactogen (bPL) have been measured in the serum of dairy and beef cattle and in the milk and amniotic fluid of pregnant animals with a highly specific radioimmunoassay. In both dairy and beef cows, serum bPL levels remain low (less than 50 ng/ml) during the first two trimesters and then rise rapidly between 160 and 200 days of gestation to a plateau. The bPL levels do not decline prior to parturition. During the last trimester, serum levels in dairy cows, 1103+/-342 ng/ml, are significantly higher than those in beef cattle, 650+/-37 ng/ml (P less than 0.01); furthermore, dairy cows having a high milk production also tend to have high bPL levels. Serum levels are almost twice as high in twin pregnancies and are not correlated with fetal sex or birth weight. bPL levels in milk and amniotic fluid from dairy cattle during the last trimester are approximately 86% and 25% of the serum values, respectively, suggesting that bPL enters these fluids by passive diffusion.

Amniotic Fluid

Artificial insemination of beef cattle.

A system for the artificial insemination fo beef cattle was described. The system involved preparation of the cattle and facilities, visual oestrous detection twice a day, drafting each morning and insemination of oestrous cows twice a day. The AI program was evaluated during the course of the program and at pregnancy test 35 to 90 days after the end of the insemination period. The insemination period was from 25 to 60 days depending on efficiency, with programs from 25 to 35 days being favoured. Results for 12218 first inseminations (65.9%) and 2222 second inseminations (57.8%) in 56 AI programs compared favourably with results in dairy AI. Pregnancy rates in lactating cows (70.5%) were significantly higher than in nonlactating cows and heifers (66.1%). Overall efficiency of well-managed AI programs were represented by 63% of cows put into a program becoming pregnant in a 29-day insemination period. Seventy-two per cent of the cows put into the program were inseminated yielding an 88% pregnancy rate. The efficiency of visual oestrous detection was 95% but this estimate did not include false positives. Efficiency of AI programs were effected by management, nutrition, infection, inseminators, facilities and the origin and type of cattle put into a program. Environmental factors such as handling, stress and thunderstorms did not effect efficiency except via a nutritional effect.

Animal Husbandry

Some causes of wastage in beef cattle artificial breeding.

Causes of reproductive loss in beef cattle AI programs were inadequate oestrus detection, use of vasectomised bulls, reduced inseminator efficiency, inadequate nutrition and infectious reproductive diseases (vibriosis and IPV). Nine case histories were presented detailing the symptoms and diagnosis of low reproductive performance.

Animals

Reproductive performance of beef cattle in northwestern Queensland.

The reproductive performance of beef cattle in 5 herds mated all year round in north-west Queensland was examined from 1970 to 1973. Conception rates, conception patterns and branding rates were used to assess annual reproductive performance. The level of loss between the times of confirmed pregnancy and branding was defined. The mean annual conception rate was 83.1% with individual property means ranging from 75.4 to 90.9%. Conception rates for heifers, first calf cows and mature cows were 83.9%, 80.6% and 84.7% respectively. Conception patterns were influenced by seasonal conditions, 68.1% of conceptions occurring in the wet season, between December and May. In this region, conception patterns were highly correlated with rainfall during the previous month. Losses between the times of confirmed pregnancy and branding ranged from 5.9 to 27.7%. Body condition of animals varied and was dependent upon lactation, seasonal and parity effects.

Animals

Estimation of economic loss associated with anaplasmosis in California beef cattle.

On the basis of questionnaire surveys and personal interviews with veterinarians, ranchers, and livestock farm advisors, the seriousness of anaplasmosis in California was determined. In 1976, the economic loss due to anaplasmosis in the study sample of beef cattle was $2,203,150. When inferences were made from the sample population to include the whole population of beef cattle, this loss was estimated to be $5,244,319. These values were in contrast to a farm advisors' estimate of $11 million loss due to anaplasmosis, which was included in a total estimated loss of $300 million due to all livestock diseases of economic importance in California. It appeared that anaplasmosis, although having a substantial economic impact in California, is not as economically devastating as it was once thought to be. It was concluded that private programs currently in use (vaccination and treatment) are sufficient to control anaplasmosis.

Anaplasmosis

A study of nephritis of beef cattle in North Queensland.

The incidence of subclinical nephritis in beef cattle slaughtered at a Townsville abattoir during the period 1970-73 was 3.8 percent. A rising incidence coincided with the wet summer of 1973-74 reaching a peak of 8.2 percent thereafter in June 1974. All but 1 of 100 cases macroscopically identified as nephritis and studied histologically proved to be of interstitial type in which lymphocytic infiltration predominated. Follicular lymphoid hyperplasia was also a common feature. The exceptional case showed proliferative glomerulonephritis. Leptospires were isolated from 16 percent of cases cultured, and observed in 8 percent of specimens examined histologically. All of the 8 isolates subjected to serogrouping were L. pomona. Of the animals tested serologically against 2 serotypes 66.2 percent were positive to L. pomona (33.8 percent), L. hardjo (18.9 percent) or both (13.5 percent). The total incidence is significantly higher than in other random surveys carried out in the region. These findings suggest that Leptospira sp. are a major cause of bovine nephritis. Since other pathogens endemic in the area, for example, Babesia and Theileria sp., may be capable of causing nephritis in cattle an accurate assessment of the aetiology of that form of renal disease in north Queensland cannot yet be made.

Agglutinins

The development in beef cattle manure of Petriedllidium boydii (Shear) Malloch, a potential pathogen for man and cattle.

Petriellidium boydii (Allescheria boydii) dominated the mycoflora of manure samples form three beef cattle feedlots after incubation at room temperature for 4 months. The possible dangers associated with this pathogenic fungus, which causes mycotic abortion in livestock, pulmonary allescheriasis in man, and mycetomas in both man and animals, are discussed. This fungus could create a health hazard in feedlots where in situ manure decompostion is encouraged.

Abortion, Veterinary

Studies on nematode infections of beef cattle in New South Wales.

The occurrence and seasonal trends of nematode parasite infections in beef cattle on the Tablelands and North Coast regions of New South Wales are described, based on worm counts from 627 spring-born steers slaughtered at 2-monthly intervals from 6 to 24 months of age. The predominant parasites were Ostertagia ostertagi, Trichostrongylus axei and Cooperia spp. Large burdens of adult Ostertagia were seen in 12-month-old animals in late winter and early spring, and later in 18- to 20-month-old cattle in the following late summer and autumn. These infections often resulted in outbreaks of clinical parasitism. Massive numbers of inhibited early fourth stage larvae (EL4) also accumulated in the yearlings during their first spring, reached peaks in mid-summer and then declined. The possibility of their resumption of development to mature worms in the late summer and autumn period is discussed. Adult T. axei showed a similar seasonal trend to Ostertagia and may have increased the severity of outbreaks of clinical disease. Cooperia populations of EL4 and adult worms were highest in weaners during winter, but lower numbers thereafter indicated a strong resistance to re-infection. In addition, Haemonchus placei occurred frequently on the North Coast both as EL4 and adults in cattle of all ages up to 20 months. Of the other cattle nematodes, Oesophagostomum radiatum and Trichuris spp occurred in low numbers, mainly in weaners. Bunstomum phlebotomum and H. contortus occurred sporadically on the North Coast and Tablelands respectively. Intestinal Trichostronglyus spp, Oesophagostomum venulosum and Dictyocaulus viviparus were seen occasionally and Nematodirus spp were not seen. There was a poor relationship between worm counts and faecal egg counts. Cooperia spp dominated the egg counts, while those for other genera were generally low and did not reflect the relative abundance or seasonal changes in worm numbers.

Animals

Supplementation of ammoniated wheat straw: performance and forage utilization characteristics in beef cattle receiving energy and protein supplements.

Two experiments were conducted to evaluate performance and forage utilization characteristics of beef cattle fed ammoniated wheat straw (AWS) unsupplemented except for minerals or supplemented with energy and protein. In Exp. 1, 194 crossbred beef cows (BW = 472 kg) in late gestation were allotted by weight, breed type, and age during two consecutive winters to 12 drylot pens (three pens/treatment) for a 60-d feeding trial. The AWS (3% NH3 wt/wt) was tubground through a 7.6-cm screen, and cows were allowed ad libitum access to the AWS. In Exp. 2, 16 ruminally fistulated Angus x Hereford steers (BW = 300 kg) were blocked by weight and randomized to treatments in a 35-d intake-digestion trial. Daily supplementation treatments in both experiments were Control, no supplemental energy or protein; LSG, 1.36 kg of sorghum grain (SG); HSG, 2.72 kg of SG; and SG + SBM, 1.02 kg of SG + .34 kg of soybean meal (SBM). All animals received .23 kg of mineral mixture formulated to meet a pregnant cow's mineral requirements. Supplements LSG and SG + SBM were fed to provide the same daily ME, and HSG and SG + SBM were fed to provide the same daily CP. Cows were managed as one group during and after calving. In Exp. 1, all supplements increased gain (P less than .01) vs Control, and cows fed SG + SBM had higher (P = .05) gains than those fed LSG. The SG + SBM supplement increased (P less than .01) change in cow body condition score compared with LSG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed

The copper status of beef cattle in Northern Ireland.

1. Serum caeruloplasmin (ferroxidase I;EC 1.16.3.1) activity has been used as an indicator of copper status of cattle to survey beef herds in Northern Ireland. 2. The main survey covered some 20 000 cows on 1200 farms. 3. The results are reported in the form of a map showing area where herds of low and very-low Cu status predominate. Clinical signs of Cu deficiency in calves were encountered in only two areas.

Animals

Beef cattle productivity under traditional and improved management in Botswana.

A comparison of productivity over a 4-year period from indigenous type beef cattle under two production systems in Botswana is reported. The two systems are: the traditional system on unenclosed communal grazing (cattle post) and ranching within fenced paddocks. Calving percentages, 7-month old calf weight, calf mortality and post-weaning growth to 18 months of age under cattle post conditions were 46.4 per cent, 122.5 kg, 10.2 percent and 88.5 kg respectively. Corresponding figures for cattle on the fenced ranches were 74.0 per cent, 177.4 kg, 8.5 per cent and 105.8 kg. These results indicate overall productivity estimates of 51 and 120 kg of weaner calf per cow per year and 86 and 188 kg of 18-month old calf per cow per year for the cattle post and fenced ranch respectively.

Animal Husbandry

The use of bovine PPD tuberculin the single caudal fold test to detect tuberculosis in beef cattle.

The efficiency of 2 different doses of bovine PPD tuberculin was compared using the caudal fold test for the detection of tuberculosis in beef cattle. Two matched groups of 98 cattle were selected on the basis of their reactivity to HCSM tuberculin. Cattle in each group were tested with a singl 0.1 ml dose of bovine PPD tuberculin containing either 0.1 mg or 0.2mg bovine PPD respectively. Two further groups of 100 young stock from a herd with an incidence of tuberculosis of less than 0.1% were selected as controls. Tests were interpreted subjectively by palpation and observation and objectively by caliper measurement at 48, 72 and 96h. All cattle were examined post mortem for the presence of visible lesions. The 0.2 mg dose of PPD detected 95% tuberculous cattle and caused false-positive reactions in 19% of cattle without lesions. The 0.1 mg dose detected 80% of tuberculous cattle and caused 11% false-positive reactions. No visible lesions of tuberculosis were found in either of the control groups although 11% reacted to 0.2 mg and 5% to 0.1 mg bovine PPD at 72h. The optimum time for reading tuberculin tests was found to be in the period 48 to 72h after the injection of bovine PPD and subjective interpretation was more efficient than caliper measurement as a means of detection of tuberculous cattle. The 0.2 mg dose of bovine PPD was found to be more specific than HCSM tuberculin.

Animals

Epiphysitis in beef cattle fattened on slatted floors.

A syndrome which causes severe lameness and affects the fetlock area of the hind limbs was recently encountered in beef cattle housed on slatted floors. This condition does not appear to have been reported to others. On radiological and pathological examination of the limb, a lesion of epiphysitis was found in the distal epiphysis of the metatarsus. The clinical, radiological and pathological features are reported and discussed.

Animals

A genome-wide assessment of the population structure of thirteen admixed and pure Australian beef cattle breeds.

Knowledge of population structure is a key factor for successful multi-breed genomic prediction, especially in single-step analysis when metafounders are considered. In Australia, current assessments mostly focus on single breeds using a single-step genomic prediction method. However, the effective integration of pedigree, phenotypic, and genomic data in a multi-breed framework still requires further research, especially for combined analyses including admixed and multi-breed populations. This study began with 602,952 genotyped individuals with 8K SNPs in common from 13 beef cattle breeds (Alexandria, Angus, Brahman, Brangus, Charolais, Droughtmaster, Hereford, Kynuna, Limousin, Santa Gertrudis, Shorthorn, Speckle Park, and Wagyu). Due to different numbers of animals being genotyped in each breed, a representative subset of animals was chosen by employing a validated sampling strategy using Gaussian Mixture Models (GMM) complemented by Principal Component Analysis (PCA) within each breed. Subsequently, a specific number of animals in each cluster were randomly selected to capture the entire genetic diversity per breed, with a total of 260 animals from each breed. The first three principal components explained 59.89% of the total variation, with PC1 (33.54%) clearly separating Bos indicus from Bos taurus lineages. Admixture analysis identified stable ancestral components and defined the genetic makeup of both pure and composite populations. The results showed extensive genetic diversity in some breeds and highlighted distinct genetic differences between Bos indicus and Bos taurus breeds. In addition, six composite breeds' admixture levels confirmed their origin and breed history, revealing a directional shift in ancestry proportions by a longitudinal increase in Brahman ancestry within tropical composites over time. Thus, the findings pave the way for more effective utilization of genetic diversity both within and across populations and provide a framework for designing multi-breed genetic evaluations and breeding programs to improve productivity and profitability in Australian beef production.

Animals

Intensive fattening of beef cattle by stall feeding on the Lilongwe Plain, Malawi. II. Utilisation of crop residues, crop by-products and leucaena.

Experiments were conducted over three dry seasons to investigate the value for fattening beef cattle, of crop residues (maize stover, groundnut haulm) and madeya (maize bran) with varying levels of dried leucaena leaf or cottonseed cake. The inclusion of groundnut haulm in the roughage increased animal performance when madeya was restricted. Increasing the protein content of the madeya supplement but restricting the quantity of madeya fed did not influence liveweight gain although the efficiency of concentrate conversion was enhanced. Restricting the amount of maize stover and feeding madeya to appetite had no significant effect on liveweight gain, but the inclusion of leucaena up to a level of 12 per cent crude protein improved animal performance. There were no differences between cottonseed cake or leucaena when fed with madeya at the same levels of crude protein.

Animal Feed