I.C. Vincent

Comparison of cortisol concentrations in saliva and plasma of dogs

It is increasingly important to have simple, non-invasive indicators of stress in animals. Studies in various species have shown that concentrations of cortisol in saliva relate closely to plasma levels of the free hormone; the aim of the present procedure was to show a similar correlation in the dog. Baseline blood and saliva samples were collected concurrently from six male beagles. Synthetic adrenocorticotrophic hormone was given and further samples were collected at 0.25, 0.5, one, two and 2.5 hours later. The results indicated a statistically significant correlation between the levels of cortisol in blood and saliva. Concentrations in saliva were between 5 and 10 per cent of those in plasma at each collection time. To demonstrate a response to a more natural stimulus, saliva samples were taken from a dog during exposure to a known stressor for that individual. The results showed a marked, delayed increase from baseline which was maintained for at least 0.5 hours after stressing.

The influence of a low-nutrient intake after mating on gestation and perinatal survival of lambs.

Abstract The effects of a low-nutrient intake during the first trimester of gestation on inutero and perinatal survival of lambs were investigated in Blackface ewes. The ewes were all in good condition (score 3 to 3 1 2 ) at the start of the experiment. The treatment group (T, 15 ewes) was given about 15% of the recommended nutrient allowances for maintenance during 60 days post mating. The control group (C, 10 ewes) was given the full maintenance allowance for the same period. At other times ewes in both groups received equal and adequate levels of nutrients. The T group lost almost 9 kg live-weight on average during the restricted feeding period and lost 0·8 unit in condition. There was some compensatory weight gain after the regime finished, but the T ewes were still a little lighter than their original live-weight by parturition. There was no evidence of embryo mortality as a result of the restricted regime. However, lambs from the experimental ewes were less viable, had a lower birth-weight and showed evidence of intrauterine growth retardation. Plasma progesterone profiles showed evidence of elevated levels in the T ewes during days 20 to 25 post coitum , significantly higher than those of the C ewes.

The effect of pregnancy and sodium intake on water and electrolyte balance in sheep

Abstract Sodium, potassium and water balance were studied throughout pregnancy in sheep on diets providing 1 mmol/kg body weight/d (H) or 0·1 mmol/kg body weight/d (L) of sodium, as well as non-pregnant controls. The polydipsia of pregnancy preceded the polyuria and the latter was greater in twin pregnancies. Faecal water loss also increased. Water turnover was particularly high in sheep excreting the majority of their sodium in urine rather than faeces; they also had greater total sodium loss at the end of pregnancy on the L diet. Sodium conservation was sustained throughout pregnancy on L diets but on H diets the increased output of urine and faeces led to increased sodium losses beyond day 90. Aldosterone secretion rose to a peak around day 100 in L sheep but was suppressed throughout pregnancy in H sheep, suggesting that this level of intake was well above requirement. The results are discussed in relation to the fluid and electrolyte physiology of pregnancy and the dietary sodium requirement.

The effects of 'adequate' and 'low' sodium intake on reproductive performance of Scottish Blackface ewes and growth of their lambs.

A low sodium diet was given to Scottish Blackface ewes over two reproductive seasons. It provided a total of 3–7 mmol sodium per day, except during lactation when the intake was about 11 mmol sodium per day. Control ewes were given the same diet supplemented with sodium chloride to Agricultural Research Council recommended concentration which was about ten times greater than that in the experimental diet. The ewes remained clinically healthy throughout the experiment. The length of gestation and the birth weight of lambs were unaffected by diet. The number of lambs born alive per ewe lambing was unaffected by year or diet. The percentage of ewes producing twins was similar in control ewes in both years at about 64; in treatment ewes this was 70% in year 1, and 50% in year 2. Lamb mortality was higher in both years in the treatment ewes than in control ewes. None of these differences reached significance.

Effects of sodium intake on lactation and Na levels in body fluids of Blackface ewes

1. A low-sodium diet was given to Blackface ewes over two reproductive seasons; the diet provided 3-7 mmol Na daily, except for the period of lactation, when Na intake was increased to around 11 mmol/d. The diet of the control ewes was supplemented with sodium chloride to provide the recommended allowance of about ten times the level in the experimental low-Na diet. 2. Milk production was assessed during the first 2 months of lactation from incremental changes in the live weight of lambs during controlled sucking periods. Na and potassium were determined in milk and also in plasma, saliva and urine. 3. Neither yield nor concentration of Na and K in milk was affected by the level of Na in the diet. These results were supported by the similarity in live-weight gain of lambs in both years regardless of diet. 4. Plasma Na and K concentrations were not affected by the level of dietary Na. Na concentration in saliva and urine was significantly lower in the treated than in the control ewes, and K concentration in saliva was significantly higher.

Effects of sodium intake during two parities on Na status in Blackface sheep

A low-sodium diet was given to Blackface ewes over two reproductive seasons. This diet provided a total of 3-7 mmol/d except during lactation when the intake was about 11 mmol/d. Control ewes were given the same diet supplemented with sodium chloride to provide recommended levels which were about tenfold that of the experimental diet. The output of Na in urine and faeces from ewes given the low-Na diet was very low, about 3 mmol/d, from early in the experiment and continued at about this level throughout. Lambs born to low-Na ewes and given a low-Na diet similar to that of their dams during lactation, grew, after weaning, more slowly than corresponding lambs from control ewes, but at 6 months of age when six from each group were killed, tissue Na contents were only slightly lower in experimental than control lambs. Fluids and tissues obtained at the end of the second lactation from four ewes of each group that had suckled twin lambs, were analysed for Na and potassium. The Na concentration in saliva and rumen fluid of low-Na ewes was about half that of control ewes and there were corresponding increases in K: the differences were significant. Although Na concentrations for experimental ewes were generally lower than those for control ewes in the tissues analysed (liver, kidney, heart, brain and bone), the difference was significant only for the heart (P less than 0.05). Haemoglobin and packed cell volume were significantly elevated in low-Na ewes (P less than 0.01), indicating decreased body fluid volume.(ABSTRACT TRUNCATED AT 250 WORDS)