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Effects of feed intake on particle distribution, passage of digesta, and extent of digestion in the gastrointestinal tract of cattle 总被引：1，自引：0，他引：1
Four nonlactating Holstein dairy cows (means +/- SD BW = 692 +/- 49 kg) were used in a 4 x 4 Latin square design experiment to determine changes in distribution of particles within the ruminoreticulum (RR) and total digestive tract in cattle fed a forage-based diet at four intake levels. Relationships between chewing activities and rates of particle breakdown, passage, and digestion were also determined. Percentage of large particles increased linearly in the dorsal rumen (P = .001), ventral rumen (P = .004), reticulum (P = .007), duodenum (P = .007), and feces (P = .006) as DMI increased. Particles of sizes less than or equal to 2,000 microns, eligible to pass from the RR, constituted 60 to 92% of particle DM in the RR. Increased feed intake resulted in a longer (P = .003) eating but a shorter (P = .008) ruminating time per kilogram of DM intake, whereas total chewing time per kilogram of DMI was not affected (P = .12). Passage rate constants of NDF from the RR increased (P = .03) with intake. There was no change (P = .87) in the rate constant for particle breakdown in the dorsal rumen with increased intake. Neither fractional passage rate of NDF nor the rate constant for particle breakdown was related to time spent eating (P + .12; P = .34) or time spent ruminating (P = .11; P = .55). It was concluded that rate of passage of small particles from the RR was a determinant of passage from the RR and that changes in rates of passage and breakdown of particles could only be partially explained by changes in chewing activities. 相似文献
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Prevalence and intensity of non-strongyle intestinal parasites of horses in northern Queensland 总被引：2，自引：0，他引：2
A quantitative post-mortem study of 57 horses from northern Queensland was done to determine the prevalence and intensity of non-strongyle intestinal parasites. The following species (% prevalence) were found: Draschia megastoma (39%); Habronema muscae (43%); Gasterophilus intestinalis (34%), G. nasalis (30%); Parascaris equorum (15%); Strongyloides westeri (6%); Probstmayria vivipara (2%); Oxyuris equi (26%); Anoplocephala magna (2%); A. perfoliata (32%). Mean parasite numbers of individual species ranged from 10 to 1310. Prevalence and intensity data were compared to recent studies in Western Australia and in the United States of America. Differences between stabled and paddocked horses were noted, particularly for botfly larvae and spiruroids. Climatic and seasonal changes in prevalence were restricted to H. muscae, G. nasalis and P. equorum with highest prevalence in the wet season or in horses from wet coastal areas. Only P. equorum showed any age effect being restricted to horses less than 5 years old. Breed and sex of horses was not important. The likelihood of changing parasite population dynamics with improved anthelmintic regimen is discussed. 相似文献
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Effects of cold environment and intake level on the energetic efficiency of feedlot steers. 总被引：3，自引：0，他引：3
The effects of cold climatic conditions on energy partitioning were investigated with 49 Hereford-type steers fed an all-concentrate, barley-based diet in a 2 x 3 factorial comparative slaughter trial. Steers (seven per treatment) were kept either indoors or outdoors (n = 2) and fed at 50, 65, or 80 g of DM/kg of BW.75 (n = 3) for up to 106 d. Mean temperatures were 16.9 +/- 2.7 degrees C and -7.6 +/- 6.8 degrees C in indoor and outdoor locations, respectively. Steers housed indoors grew 49% faster (P less than .001) and had 51% better gain: feed ratios (P less than .05) than those kept outdoors. Outdoor steers retained 65% less (P less than .001) energy. Estimated fasting heat production in the outdoor steers was 18% higher (P less than .01) and efficiency of ME use for maintenance 14% lower (P less than .01) than in the indoor steers, which resulted in an estimated increase of 41% in the ME requirements for maintenance in the outdoor steers. The NEg content of the diet was decreased from 1.29 Mcal/kg in the indoor steers to .76 Mcal/kg in the outdoor steers. Outdoor steers deposited 21% of their energy as protein, whereas indoor steers deposited only 14% of their energy as protein, which could explain the low NEg value of the diet in the cold environment. It was concluded that the main factors contributing to reduced energetic efficiency in the cold were an increased maintenance requirement and a greater proportion of the dietary energy retained as protein. 相似文献
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High level resistance to cypermethrin in the sheep body louse 总被引：2，自引：0，他引：2
GW LEVOT 《Australian veterinary journal》1992,69(5):120-120
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Strategic use of crutching and dicyclanil to protect unmulesed sheep against breech strike 总被引：1，自引：1，他引：0
Objective To test strategies for the application of dicyclanil and mid-season crutching to maximise protection of unmulesed sheep against breech strike.
Procedure Three hundred and eighty unmulesed Merino weaners were randomly allocated to four groups either left untreated or treated by different strategies with 50 g/L dicyclanil. Treatments included breech treatment alone and breech plus body treatment, with two application times, immediately after shearing and 6 weeks after crutching or shearing. To assess protection, larval implants with newly hatched Lucilia cuprina larvae were applied to 10 different sheep from each group at 3, 4, 5 and 6 months after crutching and shearing and assessed for the development of strike at 48 hours. The concentration of dicyclanil was measured in wool samples clipped from the breeches of the test sheep.
Results All dicyclanil treatments gave significant reduction in strike in comparison to controls up until 4 months after crutching but protection in the sheep treated immediately after shearing had waned at 5 months. Treating at 6 weeks after crutching provided significant reduction ( P < 0.05) in strike for 6 months. Results for strike incidence immediately after shearing and concentration of dicyclanil in the breech wool also suggested improvements in protection by delaying treatment for 6 weeks.
Conclusion In most environments it should be possible to protect unmulesed sheep against breech strike with a carefully planned integrated control program incorporating strategically timed crutching, shearing and dicyclanil application. Delaying treatment with dicyclanil to at least 6 weeks after shearing or crutching increased the protection provided in comparison to treatment immediately after shearing. 相似文献
Procedure Three hundred and eighty unmulesed Merino weaners were randomly allocated to four groups either left untreated or treated by different strategies with 50 g/L dicyclanil. Treatments included breech treatment alone and breech plus body treatment, with two application times, immediately after shearing and 6 weeks after crutching or shearing. To assess protection, larval implants with newly hatched Lucilia cuprina larvae were applied to 10 different sheep from each group at 3, 4, 5 and 6 months after crutching and shearing and assessed for the development of strike at 48 hours. The concentration of dicyclanil was measured in wool samples clipped from the breeches of the test sheep.
Results All dicyclanil treatments gave significant reduction in strike in comparison to controls up until 4 months after crutching but protection in the sheep treated immediately after shearing had waned at 5 months. Treating at 6 weeks after crutching provided significant reduction ( P < 0.05) in strike for 6 months. Results for strike incidence immediately after shearing and concentration of dicyclanil in the breech wool also suggested improvements in protection by delaying treatment for 6 weeks.
Conclusion In most environments it should be possible to protect unmulesed sheep against breech strike with a carefully planned integrated control program incorporating strategically timed crutching, shearing and dicyclanil application. Delaying treatment with dicyclanil to at least 6 weeks after shearing or crutching increased the protection provided in comparison to treatment immediately after shearing. 相似文献
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