A stathmokinetic study on the ruminal epithelium of sheep

The metaphase arresting method using colchicine was applied to a kinetic study of the proliferation of sheep ruminal epithelium. Mitotic rate, calculated from the regression coefficient of the metaphase accumulation, was 0.0025 mitoses/cell per hour. Assuming the cell cycle time is about 24 hours as reported by Goodlad (1981), the growth fraction was calculated to be about 9%. The validity of the stathmokinetic method for ruminal cell kinetics is discussed.     

A stathmokinetic study on the ruminal epithelium of sheep

The metaphase arresting method using colchicine was applied to a kinetic study of the proliferation of sheep ruminal epithelium. Mitotic rate, calculated from the regression coefficient of the metaphase accumulation, was 0.0025 mitoses/cell per hour. Assuming the cell cycle time is about 24 hours as reported by Goodlad (1981), the growth fraction was calculated to be about 9%. The validity of the stathmokinetic method for ruminal cell kinetics is discussed.     

Influence of shearing on the circadian rhythm of body temperature in the sheep

The presence of functional rhythmic variations is a well-demonstrated phenomenon at all levels of physiological organization and especially in the functioning of the cell components, of tissues and of organic systems. In domestic animals, the body temperature presents spontaneous and regular periodic oscillations over different periods of time, which are the result of complex mechanisms that witness the existence of endogenous and exogenous factors. Taking this knowledge as a starting-point, the authors studied 12 Comisana breed ewes to observe the influence of shearing on the circadian periodicity of rectal and skin temperature. The obtained results show the transient loss of body temperature rhythm by shearing, with an exogenous component, the shearing itself, and an endogenous component, the modifications of metabolic levels induced by the removal of the fleece, the external insulating layer.     

Polyamines in the gastro-intestinal tract of goat kids and in the regenerating ruminal epithelium of sheep

The aim of the present study was to investigate whether temporal changes in polyamine concentration and synthesis could be found in the luminal content and wall tissue of the rumen and abomasum, two organs which have entirely different growth patterns during the first month of life. In the abomasal mucosa there was a marked gradual decrease in the ornithine decarboxylase (ODC) activity during the first month of life, while the ODC activity in the ruminal mucosa was low during the whole experimental period. However, injury of the rumen wall was followed by increased ODC activity. The ODC activity in duodenal mucosa was about 10 times higher than in the ileal mucosa and the ruminal epithelium. In ruminal liquid a clear peak in ODC activity was observed during the period 51-70 days after birth. The polyamine concentration did not parallel the ODC activity, in either the ruminal epithelium or the ruminal liquid. Of the polyamines, the spermine concentration was always highest, and with the exception of duodenal mucosa, the putrescine concentration was lowest. In liver a clear decrease in spermidine concentration from day 1 to about day 60 after birth was observed. Otherwise no marked temporal changes in tissue polyamine concentrations were observed. Two and a half hours after oral administration of 14C-labelled spermine, nearly all of the radioactivity was found in the lumen of the gastrointestinal tract. On the other hand, 1 h after intravenous injection of polyamines the walls of the gastrointestinal tract were strongly labelled. In conclusion, the polyamines needed for ruminal epithelial development seem to come from sources other than the ruminal epithelium itself or the ruminal lumen.     

Influence of food deprivation on the transport of 3-O-methyl-alpha-D-glucose across the isolated ruminal epithelium of sheep

Recent studies provided evidence that the ruminal epithelium is able to absorb D-glucose even at physiologically low intraruminal concentrations. To elucidate whether ruminal D-glucose transport shows adaptive responses during food deprivation, transport of 3-0-methyl-alpha-D-glucose (3-OMG), a hardly metabolizable D-glucose analogue, was measured in isolated ruminal epithelia obtained from hay-fed or food-deprived adult sheep. In both groups, a significant net absorption of 3-OMG to the serosal side (in vivo: blood side oriented) could be detected at 3-OMG concentrations between 0.25 mM and 5 mM. Net absorption of 3-OMG was abolished by mucosal (in vivo: lumen side oriented) addition of phlorizin, an inhibitor of the sodium glucose-linked transporter 1 (SGLT-1). Net absorption of 3-OMG followed Michaelis-Menten kinetics, but apparent affinity and maximal transport capacity were lower in epithelia obtained from food-deprived sheep. In contrast to the decrease of the (secondary) active 3-OMG transport, serosal-to-mucosal permeation of 3-OMG increased after food deprivation, suggesting an elevated passive 3-OMG transfer. It is concluded that the altered transport characteristics are either part of a global energy-sparing process during food deprivation (i.e., a lowered activity of the Na+/K+-ATPase) or result from specific down-regulation of SGLT-1.     

Pathomorphologic changes in the ruminal acidosis of sheep]

Acute and subacute and spontaneous rumen acidosis was experimentally induced in 20 sheep and two lambs after feeding of barley, maize or glycose. The inner organs of those animals then were examined for morphological changes. The changes recorded from experimental acidosis were analogous to those observed after spontaneous outbreaks. Hyperaemia and blood leakage were macroscopically observed underneath the rumen mucous membrane which could be easily pulled off. The same signs sometimes were manifest in the third and second stomach as well. Pronounced edemas and hyperaemia occurred in the lungs, meninges (pia mater), and brain, and blood leakage was recorded from the epicardium. The histological findings included epithelial desquamation, infiltration of lymphocytes and leucocytes into rumen and fourth stomach (subacute) hepatitis (in 60 per cent of all cases), physical degeneration in the kidneys, and focal myocarditis (in 50 per cent of all cases). There were hyperaemia, edematisation, and blood leakage in the lungs, perivascular and pericellular edema in the brain, and severe hyperaemia of the meninges (pia mater) and thyroid gland. Those morphological changes were persistent and characteristic. Their relevance to diagnosis of rumen acidosis in sheep is undenied, provided that due consideration is given at the same time to the case history and paraclinical indices.     

Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis

In ruminants, the ruminal epithelium not only has the function of absorbing nutrients but also is an important tissue to prevent harmful substances in the rumen from entering the blood circulation. Thus, the normal function of ruminal epithelium is critical for ruminants. However, subacute ruminal acidosis induced by high-concentrate diets often damages the barrier function of ruminal epithelium in ruminants. Recently, many studies have shown that dietary supplementation with thiamine is an effective method to alleviate subacute ruminal acidosis. In order to provide theoretical reference for the in-depth study of subacute ruminal acidosis and the application of thiamine in the future, this review introduces the effects of subacute ruminal acidosis on morphological structure, inflammatory response, and tight junction of ruminal epithelium. In addition, this paper summarizes the role of thiamine in maintaining ruminal epithelial function of ruminants during subacute ruminal acidosis challenge.     

The occurrence of paranuclear vacuoles in sheep ruminal epithelium treated with distilled water in vitro and from sheep injected with a large quantity of water into the rumen

In the histological preparation taken after animal death, paranuclear vacuoles (PV) in sheep ruminal epithelium were already present in high percentage (7.5-20.3%). With the incubation of the ruminal mucosae in distilled water (10-15 degrees C) up to 120 min, PV occurrence did not alter. With incubation in NaCl solution, however, PV value decreased with time proportional to NaCl concentration (0.5, 0.85 or 1.5%). In the preparation taken by biopsy, on the other hand, PV were rare in ruminal epithelium (less than 0.3%). With the injection of warm water (10-141/animal), however, PV occurrence in the ruminal epithelium was not affected. PV as cytoplasmic processes of the ruminal Langerhans cells are probably formed by the reaction of these cells to environmental changes in the tissue caused by animal death.     

绵羊瘤胃酸中毒的诊疗

绵羊主要由于过食玉米、小麦等谷物饲料,于瘤胃内高度发酵,产生大量乳酸而致代谢性酸中毒.报告如下.     

The occurrence of paranuclear vacuoles in sheep ruminal epithelium treated with distilled water in vitro and from sheep injected with a large quantity of water into the rumen

In the histological preparation taken after animal death, paranuclear vacuoles (PV) in sheep ruminal epithelium were already present in high percentage (7.5–20.3%). With the incubation of the ruminal mucosae in distilled water (10–15°C) up to 120 min, PV occurrence did not alter. With incubation in NaCl solution, however, PV value decreased with time proportional to NaCl concentration (0.5, 0.85 or 1.5%). In the preparation taken by biopsy, on the other hand, PV were rare in ruminal epithelium (<0.3%). With the injection of warm water (10–141/ animal), however, PV occurrence in the ruminal epithelium was not affected. PV as cytoplasmic processes of the ruminal Langerhans cells are probably formed by the reaction of these cells to environmental changes in the tissue caused by animal death.     

A circadian rhythm of calcium intake in the domestic fowl

Observations on the food and calcium intake of six laying hens indicate that when the opportunity is provided, the fowl can control these parameters independently. The results suggest that calcium intake is regulated on an hour‐to‐hour basis by the needs of egg formation and anticipates maximal calcium requirement. Detailed records obtained from a single bird in a Skinner box suggest that calcium intake is controlled by a response to ovulation. This could be either a hormonal or a neural response.     

Presence of contagious yawning in sheep

Contagious yawning is triggered by others yawning, and it has previously been reported in humans, primates and several experimental and companion mammals. Whereas it might be a response to an innate releasing mechanism, contagious yawning is also considered to involve emotional contagion. Here, we demonstrate that sheep, the animal model of livestock animals, also experience contagious yawning. Twelve adult castrated Corriedale sheep were used in this study. Pairs of sheep were adjacently restrained with or without a wooden divider panel to shield them from viewing the other. Their behaviors were video‐recorded for 3 days in each condition. Sheep yawned 2.0 ± 1.1 and 1.2 ± 1.1 times/day/head in the unshielded and shielded conditions, respectively. Unshielded restrained sheep yawned within 1 min after the other one 11.1% of the time, while shielded pairs did not exhibit contagious yawning. Rumination was also highly synchronized under the unshielded condition. These data reveal that contagious yawning and behavioral synchronicity occur in ruminants like sheep, making them a suitable animal model to investigate contagious yawning and the underlying mechanism.     

Factors affecting the circadian rhythm in plasma cortisol concentrations in the horse

In horses, a circadian rhythm in plasma cortisol concentrations has been reported in some but not all studies. When a rhythm occurred, horses were accustomed to a management routine, comprising stabling, feeding and sometimes exercise, which may entrain a circadian pattern. In this work, we monitored plasma cortisol by collecting jugular blood through indwelling cannulae from four groups: 1): 10 untrained, unperturbed mares grazing excess pasture, bled hourly for 26 hr; 2) 4 mares housed in a barn for 48 hr before sampling every 15 min for 20–24 hr; 3) 5 mares placed in an outdoor yard for sampling every 30 min from 0930–2100 hr; and 4) 4 stabled racehorses in training, bled every 30 min from 0730–2000 hr and once the following morning at 0830 hr.Plasma cortisol showed a similarly-timed circadian rhythm (P<0.0001) in all Group 1 horses, with a peak at 0600–0900 hr, and a nadir at 1800–2100 hr. By contrast, cortisol concentrations did not vary with time in either Group 2 or 3. Neither daily mean nor peak cortisol values differed in Group 1 and 2 (i.e. bled for ≥ 20 hr); however nadir values were higher (P<0.05) in Group 2. In Group 4, cortisol declined (P=0.004) during the sampling period but had returned to initial concentrations the next morning. Values did not differ from those for Group 1, except between 1000 and 1300 hr when cortisol in Group 4 was lower (P<0.05).We conclude that a circadian cortisol rhythm exists in horses in the absence of any known cues imposed by humans. However, this rhythm can be obliterated by the minor perturbation of removing the horse from its accustomed environment. By contrast, the rhythm occurs in trained racehorses, suggesting either that they have adapted to their environment thereby allowing an endogenous rhythm to emerge, or that the rhythm is entrained by their daily routine. These observations highlight the difficulties in determining the cortisol status of a horse, since measurements will be affected by time of day, the occurrence of short-term fluctuations, and how accustomed the horse is to its environment.     

Milking frequency affects the circadian body temperature rhythm in dairy cows

The objective of this study was to investigate milking frequency as a potential stressor in Holstein–Friesian dairy cows managed in a pastoral farming system. The circadian body (vaginal) temperature rhythm was measured in cows milked twice-a-day (2x) or once-a-day (1x) in two experiments. The first experiment was conducted at peak lactation (50 ± 11 days in milk, DIM) and the second in response to a transition from 2x to 1x milking at mid-lactation (153 ± 21 DIM). At peak lactation, body temperature was continuously recorded for seven days in 40 dairy cows, milked either 2x (two groups, n = 10 per group) or 1x (two groups, n = 10 per group) from the time of calving. At mid-lactation, 60 dairy cows were milked either 2x (four groups, n = 5 per group), 1x (four groups, n = 5 per group) or switched from 2x to 1x on the afternoon of 156 DIM (2x:1x, four groups, n = 5 per group). Body temperature was measured in three of the five cows per group (36 cows in total) for 10 days from 153 to 162 DIM. Milk yield and total grazing time (Experiment 2 only) were recorded in all cows. At peak lactation cows milked 2x had a higher (P ≤ 0.051) mean body temperature between 1600 and 0000 h than 1x cows (38.6 vs. 38.4 °C; SED = 0.03 °C). At mid-lactation, mean body temperature was also elevated between 1600 and 2000 h in 2x cows compared to 1x cows (2x: 38.6 °C, 1x:38.4 °C, SED = 0.04 °C; P < 0.001) and tended (P = 0.083) to be higher in 2x cows between 2000 and 0000 h. On the day the milking frequency was switched from 2x to 1x (156 DIM), mean body temperature still tended to be higher (P = 0.087) between 1600 and 2000 h in cows continuing on 2x compared with 2x:1x and 1x cows. Body temperature in 2x:1x cows on 157 DIM was lower than 2x cows and similar to that of 1x cows, but there was no consistent effect of milking frequency on body temperature from 158 to 162 DIM. Cows milked 2x had a higher daily milk yield than 1x cows at peak lactation and at mid-lactation (peak lactation 2x: 28.1 ± 5.1, 1x: 24.5 ± 4.7 kg milk per day). Time spent grazing between 1600 and 2000 h was initially at least 22 min higher (P = 0.031) in 1x cows than in 2x:1x and 2x cows on 153 DIM but there were no differences (P ≥ 0.107) in the remaining days of the trial. Milk yield in 2x:1x cows declined rapidly on 156 DIM to be lower (P < 0.001) than both 2x and 1x cows but from 157 DIM began to follow the same pattern as 1x cows. In conclusion, milking frequency had an effect on the circadian body temperature rhythm, particularly in the late afternoon and evening. There was a decline in body temperature from 1600 h if milking frequency was reduced, but this change was not explained by treatment differences in time spent grazing during the same period. The alterations in the circadian body temperature rhythm with milking frequency were likely due to differences in metabolic activity and internal heat production associated with locomotor activity and relative milk production rather than physiological stress per se.