乳猪料的设计原则和目前可用的手段

<正>仔猪出生重约为1.4kg(品种不同,略有差异),出生后生长发育快,是生长强度最大的时期,若此阶段生长发育受阻则易形成僵猪。由于生长发育较快,需要的营养物质多,尤其是蛋白质、钙、磷、铁代谢等比成年猪要高得多,而且对     

Diagnosis of preclinical and subclinical scrapie in a naturally infected sheep flock utilizing currently available postmortem diagnostic techniques.

Scrapie is a naturally occurring transmissible encephalopathy of sheep and goats. Currently available methods for diagnosis are the presence of characteristic histopathologic changes and detection of an abnormal form of prion protein (PrPres) in the brains of affected animals. This study documents preclinical and subclinical scrapie in a flock of 16 sheep utilizing histopathology, immunohistochemistry (IHC), western blot, and electron microscopy (for scrapie-associated fibrils) for confirmation of the disease. Prior to necropsy, none of the sheep showed signs of clinical scrapie. Based on the results of histopathology and positive PrPres tests, 3 ewes were found to have subclinical scrapie. An additional ewe, which did not have histopathologic changes in the brain but was positive by IHC and western blot,was considered a preclinical case of scrapie. None of the sheep had amyloid in the brain stem.     

Recent insecticides: Their efficacy as plunge dips against the biting louse,Damalinia ovis,and the ked,Melophagus ovinus,on sheep

Abstract

Extract

At the Wallaceville Animal Research Centre, Thomas (1958 Thomas, P. L. 1958. The control of lice (Damalinia ovis) and keds (Melophagus ovinus) — a comparison of the efficiency of common insecticides. N.Z. Jl agric. Res., 1: 217–223. [Taylor &; Francis Online] , [Google Scholar]) and Greenwood (1964 Greenwood, E. S. 1964. Louse control in sheep — a comparison of seven dipping preparations. N.Z. Jl agric. Res., 7: 382–385. [Taylor &; Francis Online] , [Google Scholar]) have tested a number of insecticides against biting lice and keds on sheep. The present paper reports hitherto unpublished work by Millar (nee Greenwood) up to 1966 and more recent work carried out since her departure.     

The use of pestivirus antigen ELISA currently available for the detection of hairy shaker disease/border disease virus in sheep

AIMS: To estimate the number of cases of scrapie that would occur in sheep of different prion protein (PrP) genotypes if scrapie was to become established in New Zealand, and to compare the performance of two commercially available, rapid ELISA kits using ovine retro-pharyngeal lymph nodes (RLN) from non-infected and infected sheep of different PrP genotypes.

METHODS: Using published data on the distribution of PrP genotypes within the New Zealand sheep flock and the prevalence of cases of scrapie in these genotypes in the United Kingdom, the annual expected number of cases of scrapie per genotype was estimated, should scrapie become established in New Zealand, assuming a total population of 28 million sheep. A non-infected panel of RLN was collected from 737 sheep from New Zealand that had been culled, found in extremis or died. Brain stem samples were also collected from 131 of these sheep. A second panel of infected samples comprised 218 and 117 RLN from confirmed scrapie cases that had originated in Europe and the United States of America, respectively. All samples were screened using two commercial, rapid, transmissible spongiform encephalopathy ELISA kits: Bio-Rad TeSeE ELISA (ELISA-BR), and IDEXX HerdChek BSE-Scrapie AG Test (ELISA-ID).

RESULTS: If scrapie became established in New Zealand, an estimated 596 cases would occur per year; of these 234 (39%) and 271 (46%) would be in sheep carrying ARQ/ARQ and ARQ/VRQ PrP genotypes, respectively. For the non-infected samples from New Zealand the diagnostic specificity of both ELISA kits was 100%. When considering all infected samples, the diagnostic sensitivity was 70.4 (95% CI=65.3–75.3)% for ELISA-BR and 91.6 (95% CI=88.2–94.4)% for ELISA-ID. For the ARQ/ARQ genotype (n=195), sensitivity was 66.2% for ELISA-BR and 90.8% for ELISA-ID, and for the ARQ/VRQ genotype (n=107), sensitivity was 81.3% for ELISA-BR and 98.1% for ELISA-ID.

CONCLUSIONS: In this study, the ELISA-ID kit demonstrated a higher diagnostic sensitivity for detecting scrapie in samples of RLN from sheep carrying scrapie-susceptible PrP genotypes than the ELISA-BR kit at comparable diagnostic specificity.

CLINICAL RELEVANCE: The diagnostic performance of the ELISA-ID kit using ovine RLN merits the consideration of including this assay in the national scrapie surveillance programme in New Zealand.     

Some observations on immunologically mediated inhibited Teladorsagia circumcincta and their subsequent resumption of development in sheep

Two similar experiments were conducted with groups of yearling sheep which had been trickle infected with Teladorsagia circumcincta for 6 weeks, treated with anthelmintic then challenged with a single dose of 50,000 larvae. Ten days after challenge these sheep contained significantly fewer worms and a significantly higher proportion of arrested early fourth stage larvae than controls which had not received the trickle infection. However, by 19 or 23 days after challenge most of the arrested worms had resumed development, a process which was accelerated in a group treated with corticosteroids. It was concluded that under these conditions arrested development of Teladorsagia was a short-lived, immunologically mediated phenomenon which could be reversed by immuno-suppressing the sheep.     

Some observations on sheep sarcoptic mange in Tehran province,Iran

Sarcoptes scabiei infestation was diagnosed in 278 sheep from 12 fatling flocks. The sheep presented crusted skin lesions initially appear on the lips or nostrils, the lesion on nostrils also extend towards around the eyes, the supraorbital fossae and in some cases over entire face. The infested male lambs by mating behavior in fatling flocks caused transmitting the infection to fat tail area and scrutum. Histopathological study of lesions demonstrated marked acanthosis, hyperkeratosis, parakeratosis. Tunnels could be observed in the hyperkeratotic stratum corneum and mite segments were located mainly in the stratum corneum and also in the stratum granulosum. Attempts to eliminate S. scabiei var. ovis were made in 3 naturally infested sheep herds, by two dippings with two weeks interval with Amitraz, Cypermetrin and Prompetamphos. The results of this study indicate that acaricidal treatment of S. scabiei var. ovis in 3 naturally infested herds was successful, but a few cases of reinfestation were found in each treated group.     

The comparative efficacy of four broad spectrum anthelmintics against some experimentally induced trichostrongylid infections in sheep and goats

A controlled slaughter trial was undertaken to compare the efficacies of oxfendazole (5 mg/kg), morantel citrate (10 mg/kg), levamisole (8 mg/kg) and ivermectin (0.2 mg/kg) against experimentally induced infections of adult Haemonchus contortus, Ostertagia spp., Trichostrongylus colubriformis and Cooperiacurticei in sheep and goats. Ivermectin and oxfendazole achieved similar levels of efficacy in both hosts against all four worm genera as did levamisole and mortantel against H. contortus and C. curticei. Against Ostertagia spp. and T. colubriformis, however, the latter two drugs were less effective in goats than sheep. Neither the numbers of Ostertagia spp. removed from goats by levamisole (81% reduction) nor the numbers of T. colubriformis removed from goats by morantel (56% reduction) were statistically significant (P>0.05).     

A comparative study of feeding behavior and digestive function in dairy goats, wool sheep and hair sheep

An intake and digestibility study was conducted with three groups (six animals per group) of yearling wether dairy goats (four Toggenburg, two Alpine), wool sheep (Targhee X Dorset) and hair sheep (St. Croix). Body weight (BW) ranged from 42 to 52 kg, averaging 47 kg. All animals were penned individually and given ad libitum access to a mixture of alfalfa-smooth bromegrass hay in pelleted, chopped or long form. Each group contained three ruminally cannulated animals. There were no apparent differences in the composition of feed consumed among goats, wool sheep and hair sheep, and no significant animal type X forage form interactions for any of the variables evaluated. Significant differences were observed in dry matter intake (DMI) between wool sheep, hair sheep and goats: 3.17%, 2.66% and 2.23% of BW, respectively (P less than .05). Daily water intake (WI) was greatest for wool sheep (P less than .05), but not different between hair sheep and goats. Total digestibility of dry matter (DM) and all fiber fractions were similar among animal types. For the cannulated animals, ruminal content weight and total ruminal volume were greatest for wool sheep (P less than .05). Ruminal acid detergent lignin (ADL) turnover was greater in wool and hair sheep than goats (P less than .05), but no differences were apparent for dry matter or neutral detergent fiber (NDF) turnover. For all animals, DMI, DMI/BW, digestible DMI and WI were greater for pelleted than chopped and long hay (P less than .05). Total ruminal volume, contents weight (on an absolute or BW basis) and fluid volume were lower in the cannulated animals consuming pelleted hay (P less than .05). Ruminal DM turnover rate was faster on pelleted than long hay, while DM turnover rate on chopped hay was intermediate. Turnover of ADL was faster on pelleted than chopped or long hay (P less than .05), but there were no differences among forage forms in NDF turnover rate. Fluid turnover rate was faster on pelleted and chopped than on long hay (P less than .05). Under the conditions of this study, no apparent differences were observed among animal types in the nutrient composition of feed consumed, ruminal or total tract digestibilities or rate of passage for dry matter. However, feeding behavior or selectivity differences under natural grazing conditions may deviate from what has been observed in confinement.     

Relative efficacy of organophosphorus insecticides against susceptible and resistant strains of the strike blowfly Lucilia cuprina (Calliphoridae) in New Zealand sheep

Four groups of five Romney lambs were treated by plunge dipping with one of four registered organophosphorus flystrike preventatives. Untreated lambs acted as controls. The sheep were challenged at weekly intervals with larval implants of organophosphate-susceptible and -resistant strains of Lucilia cuprina. All four treatments provided 19-21 weeks protection against susceptible larvae but chlorfenvinphos provided the longest protection (16-17 weeks), followed by propetamphos (15-16 weeks), dichlofenthion (10-13 weeks) and diazinon (9-13 weeks), against the resistant strain.     

The efficacy of praziquantel against cestodes in cats, dogs and sheep

Praziquantel is a new type of acylated isoquinoline-pyrazine. A single, low oral or subcutaneous dose of the compound is reliably effective against all tested juvenile and adult cestodes in cats, dogs and sheep. Praziquantel is the first cestodicide which is also effective on bile duct cestodes. In cats and dogs, 5 mg praziquantel per kg is completely effective on all stages of Taenia hydatigena, T pisiformis, T ovis, T taeniaeformis, Dipylidium caninum, Mesocestoides corti, Echinococcus multilocularis and E granulosus. Because of its very wide therapeutic index praziquantel is thus particularly suited for eradication programmes, eg, echinococcosis.     

Some pharmacokinetic aspects of four sulphonamides and trimethoprim, and their therapeutic efficacy in experimental Escherichia coli infection in poultry

Pharmacokinetic studies in broilers and layers of different sulphonamides indicate a good absorption and a long elimination half-life (of sulphaquinoxaline, sulphadimidine and to a lesser degree sulphadiazine) resulting in high plasma concentrations during drinking water medication in the recommended therapeutic doses. In contrast drinking water medication with high concentrations of trimethoprim (up to 1,320 mg/liter) resulted in a maximal mean plasma concentration of 1.2 micrograms/ml. Very good therapeutic effects were demonstrated in broilers experimentally infected with a sulphonamide-susceptible E. coli strain when treated with sulphaquinoxaline (200 mg/liter), sulphadimidine sodium (2 gram/liter), sulphachloropyridazine 30 per cent (1 gram/liter) and to a lesser degree sulphadiazine sodium (250 mg/liter). Synergism was demonstrated between trimethoprim and sulphadiazine (1:5). The combination of trimethoprim with sulphaquinoxaline (1:3) did not induce better therapeutic effects than sulphaquinoxaline in proportional doses. However, significant synergism was demonstrated between trimethoprim and both sulphonamides in treatment of experimental infection with sulphonamide-resistant E. coli. No signs resembling sulphonamide intoxication were observed during these studies.     

Ophthalmoscopic characteristics in sheep and goats: comparative study

The ocular fundus was examined in 40 goat eyes and 40 sheep eyes by studying ophthalmoscopic characteristics and retinograms. Similarities and differing characteristics were described. In common: tapetal colour; peripheral yellowish area surrounding the Winslow stars; unpigmented areas in the non-tapetal zone; a great amount of myelin in the optic disc; the Bergmeister's papilla and the holoangiotic retinal vascular pattern. Differences: big size of the Winslow stars in goats; myelinizated fibre over the non-tapetal zone in sheep; shape, position and myelin distribution of the optic disc; and the presence of a 'primary artery' in goats.