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Biomedical subjects

G J Faichney

Publications and source records attributed to G J Faichney.

17 recordsLinked to original sources
PubMed1987

Effects of maternal nutritional status on fetal and placental growth and on fetal urea synthesis in sheep.

Fetal and placental growth, and fetal and maternal urea synthesis in late gestation, were studied in 2-year-old Corriedale ewes on a maintenance ration (M) except when subjected to moderate dietary restriction from day 50 to day 100 (RM), day 100 to day 135 (MR) or day 50 to day 135 (RR). In comparison with fetuses of ewes maintained throughout the experiment (MM), RR fetuses were smaller and RM fetuses were larger whereas MR fetuses were unaffected; all restrictions were associated with increased placental size. Fetal urea synthesis at day 133 in the well-nourished ewes (MM) was 21.5 mg N h-1 kg-1 increasing to, respectively, 25.7, 27.3 and 38.8 mg N h-1 kg-1 in groups MR, RM and RR; these values were 1.6, 3.9, 2.2 and 3.8 times the maternal rates of synthesis. On the basis of the observed urea synthesis rates, amino acid oxidation could have accounted for up to, respectively, 32, 38, 40 and 57% of fetal oxygen consumption in groups MM, MR, RM and RR. Amino acids, in addition to their role in tissue accretion, may be key energy substrates for the fetus.

Animals↗
PubMed1987

The role of rumen protozoa in the utilization of paspalum (Paspalum dilatatum) hay by cattle.

Six Friesian heifers (250 kg live weight) with permanent cannulas in the rumen and abomasum were allocated at random into two groups of three. One group was treated with Teric GN9 (ICI (Aust.) Ltd) to defaunate the animals during the first two of the four periods of the experiment, after which they were refaunated. The second group was treated with Teric at the end of the first two periods. The dietary treatments were: paspalum (Paspalum dilatatum) hay (4.1 kg/d) given alone and the hay supplemented with urea (20 g/kg dry matter). Defaunation was not complete but the approximate volume of protozoa in the rumen of treated animals was less than 6% of that in the untreated animals. The amount of organic matter (OM) digested in the stomach was lower (P less than 0.01) in animals with reduced fauna than in those with normal fauna. There were reductions in both the apparent OM digestibility in the total tract (from 0.56 to 0.52, P less than 0.01) and the proportion of the digestible OM digested in the rumen (from 0.82 to 0.79, not significant) of animals with reduced fauna. Apparent digestibilities of acid-detergent fibre and neutral-detergent fibre were significantly lower (P less than 0.01) in animals with reduced fauna. The amount of nitrogen disappearing from the stomach was significantly higher (P less than 0.01) with the urea supplement; effects due to concentrations of protozoa were not significant. The flow of non-ammonia-N from the abomasum was higher (P less than 0.05) in animals with reduced fauna than in animals with normal fauna. The flows of bacterial N from the abomasum and the efficiencies of bacterial N synthesis were not significantly affected by the treatments. N retention was higher (P less than 0.01) in animals receiving the urea supplement but differences due to protozoa were not significant. Protozoal contribution to the microbial N flowing from the rumen of animals with normal fauna was estimated to be 24 and 27% with and without the urea supplement respectively. Concentrations of rumen-fluid ammonia-N were reduced (P less than 0.05) and those of volatile fatty acids were increased (P less than 0.01) with reduction in protozoal numbers. Molar proportions of propionic acid increased (P less than 0.05) and of butyric acid decreased (P less than 0.01) with reduced rumen fauna.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed1986

Kinetics of nitrogen transfer across the rumen wall of sheep given a low-protein roughage.

1. The significance of blood urea-nitrogen transfer to the rumen was examined in sheep given alkali-treated wheat straw supplemented with 3.5 (diet A), 5.9 (diet B) and 11.6 (diet C) g urea-N/kg dry matter (DM). 2. Mean voluntary intakes of DM (g/d) were 897, 1149 and 1225 for diets A, B and C respectively, indicating significant (P less than 0.05) intake responses to urea supplementation. Digestion studies were conducted at 90% of voluntary intake. Dietary N intakes (g/d) were 7.1, 11.5 and 18.6 for diets A, B and C respectively. 3. Absorption of ammonia-N from the rumen (g/d) was 3.5, 6.7 and 8.9 for diets A, B and C respectively, with all dietary differences being significantly different (P less than 0.05). 4. Non-ammonia-N (NAN) leaving the abomasum (g/d) was 9.6, 12.7 and 14.8 for diets A, B and C respectively. Microbial N leaving the abomasum (g/d) was 6.8, 9.6 and 10.7 for diets A, B and C respectively. Hence, significantly (P less than 0.05) more N was provided to the intestines with increased urea supplementation. Net efficiencies of microbial protein synthesis (g N/kg organic matter apparently digested in the rumen), estimated from 15N incorporation, were 24.2, 23.7 and 25.3 for diets A, B and C respectively, and were not significantly different (P greater than 0.05). 5. Calculated proportions of microbial N derived from rumen NH3-N were 1.05, 0.95 and 0.91 for diets A, B and C respectively, reflecting the high proportion of total N as urea-N in the diets. Proportions of microbial N derived from blood urea-N were 0.31, 0.21 and 0.12 for diets A, B and C respectively, indicating a decreasing significance of blood urea as a source of microbial N as dietary urea increased (P less than 0.05). 6. Transfer of blood urea-N to the rumen (g/d) was 3.8, 4.7 and 2.6 for diets A, B and C respectively, being significantly (P less than 0.05) lower on diet C. Using an estimate of the salivary contribution of urea-N to the rumen, it was concluded that there was a significant though not large transfer of blood urea-N across the rumen wall on all diets. 7. Net transfer of blood urea-N to the rumen was estimated from a two-pool model and was +0.4 g/d for diet A, though this was not significantly different from zero.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗
PubMed1986

Effects of mild heat exposure and suppression of prolactin secretion on gastro-intestinal tract function and temperature regulation in sheep.

The effects of mild heat exposure (30 degrees C; 30% relative humidity), and of the suppression of prolactin secretion under such conditions, were studied in anoestrous ewes given daily 791 g dry matter of a pelleted mixture of lucerne hay and oat grain (3:2). 51Cr-EDTA, 103Ru-phenanthroline and lignin were used to determine mean retention times (MRT) in the gastro-intestinal (GI) tract by a continuous infusion-total sampling procedure. Mild heat exposure reduced the digesta-free tissue weight of all GI tract segments distal to the omasum. Increases in the amounts of digesta in the stomach compartments were largely due to increases in water content, although the solids content of the abomasum (P less than 0.10) and omasum also increased. The treatment caused an increase in water intake (P less than 0.10), increased the MRT of 51Cr-EDTA in the reticulo-rumen (P less than 0.05), and tended to increase the MRT of all three markers in the omasum and abomasum. However, MRT in the whole GI tract was unaffected because of a compensating decrease (P less than 0.01) in digesta MRT in the distal large intestine. Suppression of prolactin secretion with 2-bromo-alpha-ergocryptine impaired the ewes' ability to maintain their body temperature under the warm conditions imposed. This was associated with a consistent reduction in the degree to which water intake and its transactions in the GI tract changed in response to mild heat exposure. The treatment also caused decreases in omasal MRT and increases in abomasal MRT. Increased plasma concentrations of somatostatin and gastrin were associated with reduced plasma concentrations of prolactin, and it was postulated that some of the effects of prolactin on the GI tract may be mediated via somatostatin.

Acclimatization↗
PubMed1985

Gastro-intestinal tract function in sheep infused with somatostatin.

The effect of a 5-day continuous intravenous infusion of somatostatin (4.6 ng min-1 kg-1) was studied, using anoestrous ewes given 791 g dry matter per day of a 60:40 lucerne hay:oat grain pelleted diet from a continuously moving belt. 51Cr-EDTA, 103Ru-phenanthroline and lignin were used as markers to determine digesta mean retention times (MRT) by a continuous infusion-total sampling procedure. The somatostatin infusion increased the concentration of somatostatin in venous plasma within the physiological range from 10 to 76 ng/l, decreased plasma concentrations of prolactin and thyroxine, but had no effect upon plasma concentrations of insulin and glucagon. It had no effect upon digesta-free weight of the rumen and omasum but consistently decreased the weight of all post-ruminal segments of the gastrointestinal (GI) tract. The infusion increased the accumulation of digesta in the abomasum and caecum. Total MRT of all three markers in the entire GI tract was unaffected by somatostatin infusion, but the proportion of total MRT spent in the abomasum + small intestine + caecum increased and the proportion spent in the large intestine and rumen decreased. Somatostatin infusion decreased apparent endogenous abomasal secretion, increased water flow from the rumen and into the abomasum and decreased voluntary water consumption. It is proposed that the prime site of somatostatin action was in the abomasal to caecal region, where somatostatin-secreting D cells are found in greatest concentration, that effects observed in the large intestine and rumen may represent secondary compensatory mechanisms and that the effects observed were due to direct action of somatostatin and were not mediated by other GI hormones.

Abomasum↗
PubMed1985

Movement of water within the body of sheep fed at maintenance under thermoneutral conditions.

Two mature Border Leicester x Merino wethers were maintained with continuous feeding under thermoneutral conditions. Their water balance was recorded for 2 weeks; at the beginning of each week they were given a dose of tritiated water (TOH) into the pulmonary artery or the rumen and samples were taken from both the pulmonary artery and the rumen. A four-compartment model was developed which simultaneously fitted the balance and tracer data. The half-time of TOH in body water was 6.7 days for one sheep and 7.6 days for the other; TOH space was about 55% of liveweight in both sheep. The bidirectional flux of water between the plasma-accessible compartment and 'bound' intracellular water averaged 45 litres per hour and that between plasma-accessible water and rumen water averaged 3.2 litres per hour. The mean residence times of a water molecule in the rumen were, for the two sheep, 60 and 63 min and the time constants for flow from the rumen were 12.3 and 13.4 h. Consideration of the rumen water balance suggested that there was net movement of water from the rumen to the plasma at about 200 ml/h; diffusion accounted for 86% of the influx to and 92% of the efflux from the rumen.

Animals↗
PubMed1981

The utilization of lactic acid by sheep in late pregnancy.

The irreversible loss of lactate and the respiratory exchange in four conscious ewes that were about 138 days pregnant were measured at least seven days after surgery. In addition, the uptake and net output of lactate and the net uptake of glucose and alanine by the gravid uterus and an upper hind limb (primarily skeletal muscle) were measured. Calculated heat production of the ewes was 496 kJ/d.kg 3/4; irreversible loss of lactate was 9.5 mumol/min.kg of which 73% was oxidized to CO2, contributing 9% to the ewes' CO2 production. About 2% of the glucose and 65% of the alanine was derived from lactate. Lactate was taken up by both the gravid uterus and the upper hind limb; output of lactate could have accounted for from 8-12% of glucose uptake by the gravid uterus but from 35-50% of that by the upper hind limb. The carbohydrate/O2 quotient was 1.07 for the gravid uterus and 0.35 for the upper hind limb.

Alanine↗
PubMed1978

Behaviour of solute and particle markers in the stomach of sheep given a concentrate diet.

1. Fistulated sheep given a concentrate diet were used to study the behaviour of solute ([51Cr]EDTA) and particle ([103Ru]phenanthroline) markers in the stomach under conditions of continuous feeding. 2. An injection of a mixed dose of [51Cr]EDTA and [103Ru]phenanthroline was given into the rumen and the time course of marker concentrations in the rumen and the abomasum was recorded. The curves were analysed on the assumption that the stomach of the sheep could be represented as two mixing compartments (reticulo-rumen and abomasum) and a time delay (omasum). This model provided a very good description of the data. 3. [103Ru]phenanthroline associated with small particles was retained in the rumen much longer than [Cr]EDTA. Although exchange of [103Ru]phenanthroline occurred between large and small particle fractions, the results suggested that small particles may have been retained somewhat longer in the rumen than solutes. However, it was clear from the results that the mean retention times for particulate matter in the rumen could not be simply obtained using adsorbable markers. 4. Cyclical fluctuations in the concentration of [51Cr]EDTA in the rumen indicated that there were daily variations in net water flux in the rumen. 5. The presence of protozoa was associated with much shorter retention times of both solutes and particles in the rumen. Protozoa were also associated with reduced rumen volumes.

Abomasum↗