Within—country variation in the ability of ruminants to degrade DHP following the ingestion of Leucaena leucocephala—a Thailand experience

Goats fed Leucaena leucocephala (leucaena) at an experimental site in Thailand were shown to be excreting DHP in their urine. This was unexpected as earlier results from another site had shown that goats and cattle fed leucaena did not excrete DHP and so possessed DHP—degrading bacteria. Goats sampled near the earlier sample site excreted no DHP in their urine. Rumen fluid taken from these goats was successfully used to transfer DHP—degrading ability to the goats at the Experimental site some 350 km away that did not show the presence of DHP-degrading bacteria. Degradation of mimosine in-vitro and excretion of DHP in the urine ceased 72 hr after addition of rumen fluid and infusion with rumen fluid from protected goats, respectively. The situation in Thailand may not be unique. Countries where leucaena is fed should check that animals are protected. Fortunately, the ferric chloride urine test is simple to use and effective in detecting the problem and also the recovery after transfer of rumen fluid from protected animals.     

EM菌剂对银合欢草粉发酵脱毒的研究

以EM菌剂为发酵菌种,对银合欢草粉的发酵脱毒条件进行了研究。研究结果表明:有效微生物菌群能够有效降解银合欢草粉中的含羞草素,同时又使草粉保存较多的有效养分和具有较高的生物活性。有效微生物菌群处理银合欢草粉的适宜发酵条件为:发酵温度30℃,有效微生物菌群的发酵浓度2%,银合欢草粉的含水量70.47%,发酵时间35d以上,银合欢草粉的含羞草素的降解率为60%～70%,单宁降解率为60%～70%。发酵后样品中含酵母菌、乳酸菌等有益菌。     

Effects of mimosine and 2,3-dihydroxypyridine on fiber shedding in Angora goats.

The effects of intravenous infusion of mimosine or 2,3-dihydroxypyridine (2,3-DHP) and the effects of oral dose level of mimosine on fiber shedding in Angora goats were determined. In one experiment, 20 mature Angora wethers (36+/-1.9 kg BW) were infused for 2 d with 79, 102, or 135 mg/(kg BW.d) of mimosine, 90 mg/(kg BW.d) of 2,3-DHP, or saline. At 7 d after infusion began, fiber shedding was observed in all goats receiving mimosine but not in any goats infused with 2,3-DHP or saline. Fiber shedding varied among goats; in some goats, fiber shedding was complete and occurred without hand-plucking, whereas in others fiber was retained by nonshed fibers but could be removed by hand-plucking. Nonshed fibers were larger in diameter and more likely to be medullated (P < .05) compared with hand-plucked fibers. Mean plasma mimosine concentration at 24 and 48 h after infusion began was 79 and 98 micromol/L (P < .05), respectively, and greater (P < .05) for mimosine infused at 135 than at 102 mg/(kg BW.d) (89, 68, and 108 micromol/L for mimosine infused at 79, 102, and 135 mg/[kg BW.d], respectively; SE 9.5). In another experiment, oral dosing of eight Angora bucks (23+/-.5 kg BW) with 400 or 600 mg/kg BW of mimosine rapidly increased plasma mimosine concentration, which reached approximately 100 and 160 micromol/L at 5 h after dosing; however, periods of time during which plasma mimosine concentrations were comparable to those in the first experiment were considerably shorter. Oral mimosine dosing did not induce fiber shedding in 7 d. After 31 d, fiber was retained by nonshed fibers but could be removed by hand-plucking or could only be partially removed with difficulty by hand-plucking. There were no toxic effects of mimosine or 2,3-DHP administration; only minor, short-term inhibitions of feed intake by mimosine were noted in some goats. In conclusion, mimosine holds promise as a safe means to remove fiber of Angora goats; further research is necessary to characterize the seasonality of follicle activity and to develop convenient means of mimosine delivery.     

Successful transfer of DHP-degrading bacteria from Hawaiian goats to Australian ruminants to overcome the toxicity of Leucaena

Cattle and goats in Australia lack the ability to totally degrade 3-hydroxy-4(1H)-pyridone, also known as 3,4-dihydroxy pyridine (3,4 DHP), the ruminal metabolite of mimosine, a toxic aminoacid present in the leguminous shrub Leucaena leucocephala. Ruminants in Hawaii have this capacity due to the presence of micro-organisms able to rapidly degrade the DHP. A mixed bacterial population capable of rapidly degrading DHP in vitro was isolated from a goat on the island of Maui. Cultures were grown anaerobically, without added sugars, in Medium 98-5 containing DHP. Cultures at a dilution of 10(-12) from the original rumen fluid were introduced into Townsville and further sub-cultured and multiplied in vitro in strict isolation at the Oonoonba Veterinary Laboratory, Townsville. Infusion of the culture into a goat and a steer fed a 100% leucaena diet resulted in cessation of DHP excretion in the urine. After 60 days the serum thyroxine levels and thyroid size were normal and there were no clinical signs of disease. The ability of the rumen fluid to degrade DHP in vitro showed that the bacteria had become established in the rumen. In the absence of any disease in the animals, clearance has been given for the wider use of these cultures in areas where leucaena is grown. The limited evidence suggests that the leucaena toxicity problem can be solved by the use of these introduced bacteria.     

Genotype X environment interaction in Hereford cattle: IV. Postweaning traits of bulls

Genotype X environment interactions for postweaning performance traits of bulls produced by different lines of Hereford cattle were investigated in the contrasting environments of Miles City, Montana and Brooksville, Florida. During Phase 1 of the study (1966 to 1973), the performance of bull progeny from two unrelated lines (M1 and F6 previously developed in Montana and Florida, respectively) was compared at each of the two experimental sites. During Phase 2 (1967 to 1974), performance of bulls from two related lines (M1 of Montana origin and F4 derived from an M1 foundation through selection in Florida) was compared at each of the two locations. The line X location interaction effect in Phase 1 was highly significant for weaning weights and average daily gain during the postweaning test, and for end-of-test weight, conformation score, condition score and forecannon circumference. The interaction effect in Phase 2 was highly significant for 205-d and end-of-test weights and significant for all other traits except end-of-test conformation score. These results, consistent with results for traits covered in other papers of the same series (reproductive traits, birth-to-weaning traits of bull and heifer calves combined, and postweaning traits of heifers), indicated the existence of economically important genotype X environment interactions in beef cattle. Results from the series of papers indicated that adaptation to local environment should receive consideration in planning breeding programs, performance tests and interregional transfers of beef cattle.     

The infectivity of surviving Psoroptes ovis (Hering) on cattle treated with ivermectin

Ivermectin, 22,23-dihydroavermectin B1 (Merck MK-933), injected intramuscularly at the rate of 200 microgram kg-1 body wt., completely eliminated Psoroptes ovis populations from 6 Hereford cattle within 2 weeks after treatment. However, mites surviving 1, 3, and 5 days after treatment were viable and infective when transferred to untreated cattle. Mites surviving 7 days after treatment did not cause scabies or establish a colony of mites when transferred to untreated cattle. These results indicate that cattle treated with ivermectin for control of psoroptic scabies should be isolated from other cattle for at least 5 days after treatment.     

Growth and muscle development of feedlot cattle of different genetic backgrounds

The effects of crossbreeding, cattle type and dietary energy level on semitendinosus muscle (ST) development, feedlot performance, daily carcass protein and fat gain and serum anabolic hormone concentrations were studied. Over 3 consecutive years, 176 feedlot steers representing four cattle types - unselected Hereford (UH), selected Hereford (SH), Angus x Hereford x Charolais (AHC) and Angus x Hereford x Holstein (AHH) - were fed either an all-corn silage (HS) or a high grain (HG) diet. Steers were slaughtered on day 1 and at the end of the feedlot trial, and ST muscles were removed rapidly. During years 2 and 3, single blood samples were obtained from steers on days 1, 29, 57, 113 and 169, and analyzed for insulin and growth hormone (GH). Steers fed HG had a higher (P less than .005) average daily gain (ADG) than steers fed HS, and cattle type had an effect (P less than .005) on ADG. Cattle type and HG affected (P less than .005) daily carcass protein and fat gain. Weight of ST muscle and total muscle RNA, DNA and protein content increased with frame size, and HS steers had heavier (P less than .05) ST muscles than the HG steers. Steers fed HG had higher (P less than .01) serum insulin concentrations than steers fed HS, but there were no consistent cattle type effects. Serum GH concentrations were not affected by cattle type or diet. Serum insulin concentrations, combined across diet and cattle types, were correlated (P less than .01) with ADG; however, serum GH, assessed on the same basis, was not related to ADG. Average daily protein and fat gain were positively related to serum insulin and were negatively related to serum GH.     

CONTROL OF THE BUSH TICK (HAEMAPHYSALIS LONGICORNIS) WITH ZEBU X EUROPEAN CATTLE

SUMMARY Brahman x Hereford cattle carried only one-quarter as many engorging adult bush ticks ( Haemaphysalis (Kaiseriana) longicornis ) as Hereford, Simmental x Hereford or Friesian x Hereford cattle when grazed together on the north coast of New South Wales. Fourteen percent of a Brahman x Hereford herd carried half of the engorging ticks suggesting that infestation levels would be further reduced by culling procedures. The results indicate an additional advantage to those already established for Brahman x Hereford cattle on the north coast of New South Wales and have important implications for tick control.     

Effect of monensin and a protonophore on protein degradation, peptide accumulation, and deamination by mixed ruminal microorganisms in vitro

Mixed ruminal bacteria (80 mg N/liter) degraded casein and soluble soy protein rapidly (.68 and .72 mg N/[liter.min], respectively), but ammonia was produced at a slower rate (.08 and .10 mg N/[liter.min], respectively). Because there was little increase in cell protein, ammonia production could not account for all the degraded protein. Large quantities of non-ammonia, non-protein nitrogen (NAN-NPN) accumulated, and this NAN-NPN reacted more strongly (2- to 14-fold) with ninhydrin after it was treated with 6 N HCl (110 degrees C, 24 h) or pronase E. Even after 96 h of incubation, 10% of the protein N was still found in the NAN-NPN pool. Monensin had little effect on protein degradation, but it caused a large decrease in ammonia production (P less than .05) and an increase in NAN-NPN (P less than .05). These results indicated that significant quantities of peptide N could not be degraded by ruminal microorganisms and that monensin could increase peptide flow from the rumen. Because 3,3',4',5-tetrachlorosalicylanide, a protonophore that inhibits both Gram-positive and Gram-negative bacteria, did not cause a greater decrease (P greater than .05) in ammonia than monensin, an ionophore that is primarily effective against Gram-positive bacteria, it seemed that the "protein sparing" of monensin could largely be explained by its inhibition of Gram-positive bacteria.     

A SURVEY OF DYSTOCIA IN BEEF CATTLE IN SOUTHERN QUEENSLAND

Data relating to dystocia were obtained for 22% of beef herds in the Roma region of southern Queensland. In 1973 dystocia incidence in 23,129 maiden heifers was 12%; 4% of heifers and 7% of calves died. Thirty-five per cent of the 444 herds surveyed had more than a 10% incidence of dystocia, and 10% had more than a 30% incidence of dystocia. Only 6% of herds had no dystocia. Among the 73% of producers considering dystocia a problem in most years, 14% regarded it as a major problem. The incidence of dystocia in heifers was significantly higher in Poll Hereford than Hereford herds, which in turn were higher than other breeds of cattle. Poll Hereford and Hereford owners were the most concerned about dystocia but did not supervise calving more frequently. Dystocia and attitude were also examined in relation to degree of supervision at calving and size of the breeding herd.     

Variation in the Percentage of Female Births over Time in Five Breeds of Registered Beef Cattle1

Breed and sire effects on the percentage of female births over time in five breeds of registered beef cattle were studied. Breed groups were managed separately, and matings were performed by artificial insemination and natural service. The percentage of female births was included in the study for sires that were used for at least 2 yr and sired at least seven progeny. Progeny of 48 Angus, 7 Charolais, 19 Horned Hereford, 17 Polled Hereford, and five Red Poll sires were used in the study. The numbers of birth years by breed were 33, 21, 31, 31, and 15 for Angus, Charolais, Horned Hereford, Polled Hereford and Red Poll, respectively. Variances for breed and sire were partitioned for percentage female births using a nested random effects analysis of variance. Breed effects for percentage of female births were 0.46% of total variance. Sire effects accounted for 0.27% of total variance. Means for percentage female births by breed were 50 ± 1% for Angus, 47 ± 3% for Charolais, 48 ± 2% for Horned Hereford, 52 ± 2% for Polled Hereford, and 49 ± 5% for Red Poll. Although sire variance was minimal, there were some sires that consistently produced a greater or lesser number of females over time. These results suggest that more research is needed to determine the factors that influence sex ratio in cattle due to its economic importance to the industry.     

Differences in grazing behavior of horses and cattle at the feeding station scale on woodland pasture

In this study, grazing behavior of mares and cows was compared on woodland pastures, in the context of foraging hierarchy. A horse‐group (12 native Hokkaido horses) and a cattle‐group (5 Hereford cows) were grazed on the woodland pastures of 13.3 ha and 5.8 ha, respectively. They grazed mainly on Sasa nipponica. Grazing behavior at a feeding station (FS) scale was recorded for three focal animals in each group. Mares took one bite per FS at a high percentage of FSs (24.3%) and cows took one, two and three bites per FS at high percentage (20.3%, 19.2% and 15.4%, respectively). Although feeding patch (FP) scale for both animals could be defined as a group of FSs, the length of FP and grazing behavior at FP scale were similar for both animals. The number of steps taken between two adjacent FSs or FPs for mares was larger than that for cows. The results suggested that both horses and cattle had similar foraging hierarchy from bite to FP scale but grazing behavior of horses at the FS scale was different from that of cattle, suggesting that grazing behavior of large herbivores has greater similarity in larger foraging hierarchies.     

夏海黄三元杂种牛生长发育研究

测定分析了夏海黄三元杂交后代（公牛３４头，母牛３７头）与豫北黄牛及海黄Ｆ１初生－２４月龄体尺与体重均较豫北黄牛有较大幅度提高，较海黄Ｆ１提高明显，利用夏海黄三元杂交发展肉牛生产是一条有效途径。     

The Effect of Scours on Calf Weaning Weight

Beef cattle health and performance records of 3637 calves from inbred and outbred populations were evaluated to determine the effect of scours on weaning BW (WW). Animals were maintained under similar environmental conditions at the Northern Agricultural Research Center near Havre, Montana. Inbred animals were linebred Hereford cattle with an average inbreeding coefficient of 0.20. Outbred animals were Hereford, Angus × Hereford, Simmental × Hereford crosses and backcrosses, and Tarentaise × Hereford crosses and backcrosses. Weaning BW was analyzed by least squares ANOVA. Model included year, age of dam, line (inbred or outbred), scours, and date of birth as a covariate. When zero WW were included for calves that died of scours (1%), all main effects were important. The least squares mean WW were 208 and 217 kg for scouring and non-scouring groups, respectively. Interactions between year × age of dam (P < 0.01) and year × line (P < 0.01) were detected. Incidence of scours was analyzed by the CATMOD procedure of SAS. The model included year, age of dam, and line (inbred or outbred). All main effects were important (P < 0.01). Incidence of scours ranged from 13% in 1982 to 64% in 1991. Incidence of scours was greatest in calves born to 2-yr-old dams with probabilities of 47% and 33% in inbred and outbred dams, respectively. These results indicate that scours negatively influenced WW. Incidence of scours was greater in calves born to younger dams and for inbred cattle.     

ELECTIVE CAESAREAN OPERATION IN HEREFORD CATTLE

An elective left flank Caesarean operation was performed on 56 Hereford cattle and the influence of various surgical techniques on the postoperative progress assessed. A paravertebral nerve block produced effective analgesia in all layers of the abdominal wall of all cattle. In contrast, tissue infiltration, in the form of an inverted L block, did not produce analgesia of the peritoneum and was generally only partly effective in the muscle layers of fat animals. The use of spasmolytic drug facilitated handling of the uterus. Xylazine, when given to unmanageable animals, noticeably increased uterine tone even when used in conjunction with a spasmolytic. Three animals (5.4%) died from generalised peritonitis. Peritoneal adhesions developed in 29 animals (51.8%) and minor wound dehiscence and/or suture infection occurred in 8 animals (14.1%). Postoperative subcutaneous emphysema developed in ;23 cattle (41%). The absence of sutures in the peritoneum was associated with a significant increase in the occurrence of subcutaneous emphysema. Although the prevalence of retained foetal membranes was high this did not seem to influence the postoperative progress of the animal.     

Mineral and amino acid composition of beef cattle hooves

Twenty-three Hereford X Shorthorn cattle were used to evaluate the effects of seasonal and dietary changes on the mineral composition (Ca, Mg, Cu, Zn, and S) of hooves. A seasonal pattern was found in the Ca, Mg, and Zn composition of hooves in the 12 cattle evaluated in 1982 and in the 11 cattle evaluated in 1983, with the concentrations of 3 minerals decreasing in winter when dietary change did not occur. Copper concentrations significantly decreased during the 1st year (1982) and had a tendency to decrease during the 2nd year. During the 1983 pasturing season, when effects of seasonal vs dietary change could not be distinguishable, hoof concentrations of Ca and Mg decreased, whereas the inverse trend was observed for Cu and Zn. Seasonal patterns for hoof concentrations of S were not found. Results of mineral analysis of hooves indicated strong correlations between calcium and the other minerals (except S), and between Zn and Cu. Amino acid analyses of hooves of the 11 cattle in 1983 indicated differences in their composition related to dietary changes (winter feeding vs pasture) or to management.     

Putative quantitative trait loci associated with the probability of contracting infectious bovine keratoconjunctivitis

Infectious bovine keratoconjunctivitis, also known as pinkeye, is an economically important disease in cattle. The objective of this study was to detect QTL associated with infectious bovine keratoconjunctivitis in offspring from a Brahman x Hereford sire. The sire was mated to Hereford, Angus, and F1 cows to produce 288 offspring in 1994 and mated to MARC III ((1/4) Hereford, (1/4) Angus, (1/4) Red Poll, and (1/4) Pinzgauer) cows in 1996 to produce 259 offspring (547 animals total). Infectious bovine keratoconjunctivitis was diagnosed by physical examination in 36 animals of the family. Records included unilateral and bilateral frequency, but not severity. Records were binary: 0 for unaffected and 1 for affected cattle. A putative QTL for infectious bovine keratoconjunctivitis was identified on chromosome 1, with a maximum F-statistic (F = 10.15; P = 0.0015) at centimorgan 79 of the linkage group. The support interval spanned centimorgans 66 to 110. There was also evidence suggesting the presence of a QTL for infectious bovine keratoconjunctivitis on chromosome 20, with a maximum F-statistic (F = 10.35; P = 0.0014) at centimorgan 16 of the linkage group. The support interval ranged from centimorgan 2 to 35. This report provides the initial evidence of QTL for infectious bovine keratoconjunctivitis. Although a candidate gene was identified for one of the regions of interest, further studies are needed to identify the genetic basis of resistance to the disease.     

Introduction of bovine hypodermiasis (Hypoderma bovis) with the importation of Hereford cattle from Canada

The infestation by warble-fly (Hypoderma bovis /De Geer/) larvae was observed in Hereford cattle imported from Canada to Czechoslovakia in the autumn 1974. A risk of introducing hypodermosis in the areas where it had been eradicated occurred after a several-year persistence of such foci of the disease. The original infestation of the imported cows corresponded to the invasion extensity of 22 to 45% and invasion intensity of 1.9 and 3.7 larvae. There were observed no differences in the degree of infestation in cattle from different regions of Canada. In the subsequent years the invasion extensity in heifers was 52% the invasion intensity was four larvae. To control hypodermosis, Czechoslovak chemicals Arpalit-Spray and Hypocide were applied to Hereford cattle. In the West Bohemian Region cattle was treated with the chemical Arpalit-Spray in spring for three years to eradicate hypodermosis in the Tachov and Susice districts. A good result was obtained after the treatment in May during the maximum occurrence of larvae in bulges under the skin, the treatment in June was late and inefficient. In the Central Slovakian Region, Dolny Kubín district, hypodermosis was eradicated in Hereford cattle by a repeated treatment with Hypocide in autumn. The control of hypodermosis in Hereford cattle in the Prievidza district failed. In 1979 the invasion extensity in heifers was 25-100%, the invasion intensity was 2 to 25 larvae. Cattle transferred from this herd to the Lucenec, Presov and Gottwaldov districts were also infested. In the Gottwaldov district in the South Moravian Region all infested cows were treated with Arpalit-Spray in the summer 1979.     

Effect of postmortem treatments on the tenderness of meat from Hereford, Brahman and Brahman-cross beef cattle

The effect of postmortem aging (7, 14, 21 or 28 d), high-voltage electrical stimulation (stimulated or not stimulated) and blade tenderization (none or once; crossbreds only) on the sensory and cooking properties of meat from four beef breeds or breed-types (purebred Hereford, purebred Brahman, Hereford x Brahman and Brahman x Hereford) was determined. The meat from purebred Brahman cattle that was not electrically stimulated was less tender and more variable in tenderness than that from other breed-types but electrical stimulation reduced these differences in tenderness. The Brahman crossbred steers produced meat that was not different in tenderness or variability in tenderness from that of purebred Hereford steers, although all were only judged "slightly tender." Electrical stimulation reduced the length of postmortem aging needed to reach a given level of tenderness regardless of breed or breed-type. Meat from crossbred animals that was blade-tendernized was not different in tenderness from meat that was electrically stimulated. The results of this investigation indicate that purebred Brahman muscle was inherently less tender, but postmortem tenderization procedures produced meat that was similar tenderness to that of the other breed-types used in this study.     

Description of a scale for rating the clinical response of cattle poisoned by larkspur

Larkspur poisoning is a major cause of acute death of cattle on mountain and high plains rangelands of western United States. A nonlethal method to quantify dose response in cattle is needed to better estimate the toxicity of larkspur plants and the response of cattle to larkspur poisoning and to provide a basis for reference during studies. A numerical system of rating the clinical signs of larkspur poisoning was developed and used to describe the response of 10 Hereford cows given a repeated single daily dose of larkspur (Delphinium occidentale x barbeyi) by gavage. Larkspur poisoning resulted from a short-term cumulative effect, and a statistically significant increase in score was essentially maximal by 4 days. At the dose given, this effect did not persist for more than 4 days after cessation of dosing. Poisoning was most severe between 5 and 9 hours after dosing. Early signs of poisoning can be subtle and sometimes brief. The effect of larkspur poisoning can be exacerbated temporarily by exertion. Therefore, cattle could probably repeatedly consume an otherwise toxic daily dose, without manifesting marked signs of poisoning, if consumption decreased to a sufficient degree intermittently at 2- to 4-day intervals.