An omaso-abomasal cannula used to assess efflux from the omasum of sheep

Evaluation of the spot urine sampling technique to assess urinary purine derivative excretion in lactating dairy cows

The potential of the spot urine sampling technique as an alternative to performing a total urine collection was evaluated. Twelve multiparous Holstein-Friesian cows were given two experimental diets in a complete change-over design using two 14-day experimental periods. Experimental diets were either silage offeredad libitumwith 7 kg fresh weight concentrate supplement as a single meal (SF), or a complete diet formulated from the same ingredients with a similar foragexoncentrate ratio (CD). Total urine collections were performed every 2 h on days 11 and 14 of each experimental period. Subsamples of urine were stored at 20°C and subsequently analysed by high-performace liquid chromatography. Daily allantoin and purine derivative (PD) excretion were highly correlated (r = 0·995, no. = 48,P< 0·001). PD and creatinine excretion during each 2-h interval depended on time of collection (PD,P< 0·001 and creatinine,P< 0·05) and on cow (P< 0·01) but were unaffected by sampling day or treatment. Diurnal variations in the molar ratio ofPD or allantoin to creatinine (PD/c and Ale, respectively) followed similar diurnal patterns as observed for PD and allantoin excretion. The data were used to assess the error of prediction of daily mean PD/c or Ale ratios. Three spot sampling regimens (based on the collection of four 4-h samples, three 8-h samples or two 12-h samples) and also on either single or 2-day urine collections were evaluated. Collection of multiple samples within a day was more reliable than collecting fewer samples over several days. Prediction errors were greater for SF compared with CD. Even the most intensive sampling regimen did not allow an acceptable prediction of daily mean PDIc or Ale ratio, minimum r values for PDIc and Ale ratios were 0·098, 0·136 and 0·547, 0·579 for SF and CD, respectively. Furthermore, daily mean PDIc and Ale ratios proved poor predictors of daily PD and allantoin excretion (r values of 0·69 and 0·72, respectively). Total urine collection appears necessary to assess accurately daily PD excretion in dairy cows.

Access to the abomasum of sheep via a rumen fistula for follow-up studies during trichostrongylid infections

A technique is described for the examination of the abomasum of adult sheep via a rumen fistula. The size of the fistula allowed a manual exploration of the rumen which was necessary to achieve an access to the abomasum. In four adult sheep, two of them infected with Haemonchus contortus, fibreoptic endoscopy was used to investigate the abomasal mucosa macroscopically as well as histopathologically and ultrastructurally by means of mucosal biopsy specimen. The acidity of the abomasal contents was measured directly by introducing an electrode into the abomasum or indirectly in abomasal fluid which was obtained via a stomach catheter through the rumen fistula. The measured values in all four sheep ranged between pH2 and 4. The fibreoptic examination of the abomasum did not influence the plasma pepsinogen and gastrin levels. The possibility of combining histological, serological and coprological data in follow-up studies on the pathophysiology of trichostrongylid infections in the abomasum of individual sheep seems to be useful for the investigation of primary and secondary infections and may contribute to a reduction of the number of experimental animals in such studies.

Omasal ciliated protozoa in cattle, bison, and sheep

Omasal contents were collected from slaughtered cattle (n = 54), bison (n = 15), and sheep (n = 40) to determine numbers and generic distribution of ciliated protozoa. Total protozoan numbers were significantly lower in omasal contents than in ruminal contents of all three species, but the percent composition of all protozoan genera was similar between omasal and ruminal populations. The highest numbers of omasal protozoa found were 7.61 X 10(5)/g in cattle, 7.01 X 10(5)/g in bison, and 1.29 X 10(6)/g in sheep. Omasal dry matter was significantly higher than ruminal dry matter in all species and ranged up to 51.5% in cattle fed high-concentrate diets. The omasal pH was similar to the ruminal pH in all species. The number of omasal laminae averaged 149, 145, and 74 for cattle, bison, and sheep, respectively. Although protozoan concentrations in omasal contents were approximately 80% lower than those in ruminal contents, the omasum harbored relatively high numbers of ciliated protozoa. The resident omasal protozoa are extremely difficult to remove, particularly in cattle, and apparently are responsible for reinoculating transiently defaunated rumens.

Reticulo-ruminal motility in cattle (Bos indicus) and water buffaloes (Bubalus bubalis) fed a low quality roughage diet

1. The effect of A and B sequence contractions of the reticulo-rumen on passage rate of digesta was compared in buffaloes and cattle fed low quality rhodes grass. 2. Both species ate the same amount per unit body weight but buffaloes spent 53% more time ruminating than cattle. 3. Buffaloes had fewer A and B sequence contractions each day and the rate of these contractions during eating, ruminating and at rest were slower. 4. A larger pool of fine feed particles in the rumen of buffaloes, generated by extra ruminating activity was associated with the 30% shorter mean residence time of particulate matter in the forestomach compared with cattle. 5. It is concluded that the difference in the number and frequency of contractions between the species was insufficient to affect passage rate of digesta from the stomach.

The significance of water absorption and fibre digestion in the omasum of sheep, goats and cattle

1. The omasal dry matter contents constituted 0.6, 1.2 and 3.3% of the body weight in the sheep, goats and cows, respectively. 2. A large part of the fluid leaving the reticulo-rumen passed quickly through or along the omasum to the abomasum in sheep (43%). The proportion was much less in goats (17%). 3. The absorption of water from the fluid delayed in the omasum was low: 15, 18 and 19% in sheep, goats and cows, respectively. 4. Little or no acid detergent fibre was degraded in the omasum.

A comparative study of the anatomy of the omasum in domesticated ruminants

The structure of the omasum was compared in 10 water buffalo (Bubalus bubalis), 10 Shorthorn cattle (Bos indicus), 9 Merino sheep (Ovis aries) and 10 cross-bred goats (Capra hircus), and the functional significance of the differences is discussed. The weight of the omasum and area of the internal laminae appeared to be smaller in Brahman cattle than the buffalo and British cattle. When compared in relation to body weight, the omasums of caprid animals were smaller than those of bovids, by a factor of 0.33-0.67 but the omasums of goats were appreciably larger than sheep. The number of laminae ranged from 33 to 35 for the sheep and goats compared with 122 to 169 for the buffalo and cattle. It is suggested that the marked difference in structure of the omasum between the small and large ruminants may influence the food intake of these animals through the effects of this gut compartment on absorption of nutrients and passage of digesta.