Concentrations In Lambs Research Articles

Effects of monensin on monovalent ion metabolism and tissue concentrations in lambs.

A study consisting of two trials was conducted to determine the effects of monensin on the apparent absorption and retention of sodium (Na) and potassium (K) and to examine changes in tissue and ruminal fluid concentrations of these minerals in lambs. Eight lambs (39 kg) were used in trial 1 and 10 lambs (37 kg) were used in trial 2. Animals were used in randomized block designs, blocked by weight, and fed a high concentrate diet with or without 20 mg/kg monensin. Trials began with a dietary adjustment period lasting 18 d in trial 1 and 21 d in trial 2. Animals were then placed in metabolism stalls for a 10-d stall adjustment period followed by a 12-d collection period. Collections for mineral balance were made during the first 10 d of the collection period. Blood and ruminal fluid samples were obtained on d 11 of the collection period. Lambs were slaughtered on d 12 of the collection period and tissue samples were collected. Sodium retention decreased (P less than .05) 86.2% when monensin was fed. Apparent K absorption increased (P less than .05) 16.7%, while K retention increased (P less than .10) 52.6% when monensin was fed. In lambs fed monensin, ileal Na decreased (P less than .10) 13.8%. These results indicate that dietary monensin alters the metabolism of Na and K in lambs.

Effects of monensin on Mg, Ca, P and Zn metabolism and tissue concentrations in lambs.

A study consisting of two trials was conducted to determine the effects of monensin on the apparent absorption and retention of magnesium (Mg), phosphorus (P), calcium (Ca) and zinc (Zn) and to determine mineral changes in tissue and ruminal fluid. Eight lambs (39 kg) were used in trial 1, and 10 lambs (37 kg) were used in trial 2. Animals were blocked by weight and fed a high concentrate diet with or without 20 mg/kg monensin. Trials began with a dietary adjustment period lasting 18 d in trial 1 and 21 d in trial 2. Animals were then placed in metabolism stalls for a 10-d stall adjustment period followed by a 12-d collection period. Collections to determine mineral balance were made during the first 10 d of the collection period. Blood and ruminal fluid samples were taken on d 11 of the collection period. Lambs were slaughtered on d 12 of the collection period and tissue samples were collected. Monensin supplementation increased (P less than .05) Mg retention 42.0%. Urinary Ca excretion decreased (P less than .05) 60.0% when monensin was fed. Monensin supplementation decreased (P less than .05) liver Ca and bone Ca, 45.5 and 2.9%, respectively. Apparent P digestibility increased (P less than .05) 40.0% and P retention increased (P less than .10) 26.8% due to monensin supplementation. Both apparent absorption and retention of Zn increased (P less than .01) 50.0 and 45.0%, respectively, with monensin supplementation. Ruminal fluid Zn concentrations decreased (P less than .05) 33.0% with the addition of monensin.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma catecholamine concentrations in lambs and calves during the perinatal period.

Concentrations of the plasma catecholamines (CA), adrenaline, noradrenaline and dopamine, were measured using a specific and sensitive radioenzymatic assay in 7 ewes and their single lambs chronically catheterized in utero between days 127 and 145 of gestation and during the first week of postnatal life. These concentrations were also measured during the first month after birth in 18 Holstein x Friesian calves, of which 9 were born spontaneously at term (278 days) and 9 by caesarean section on day 260 of gestation. Plasma CA concentrations in ewes showed no significant variations during the sampling period. Plasma adrenaline, noradrenaline and dopamine concentrations in lambs at birth rose significantly to 1 800 +/- 520, 3 782 +/- 781 and 575 +/- 90 pg/ml, respectively. These values remained higher than those measured in ewes until 2, 24 and 48 h after birth, respectively. On days 5 and 10 after delivery, plasma dopamine and noradrenaline concentrations were higher in calves delivered by caesarean section than in those born spontaneously at term, while plasma adrenaline concentration was never different between the two groups. These results indicate that the surge in plasma CA concentration normally occurring at birth might be delayed post partum in animals delivered before term. This might partly explain why these animals were less resistant to stress during the first days of postnatal life.

Genetic and non-genetic effects on plasma LH concentrations in lambs at 4 and 8 weeks of age.

Plasma LH was measured at 4 and 8 weeks of age in purebred lambs born to Finnish Landrace, Galway, Fingalway and High Fertility ewes. The average litter sizes for these breeds vary from 1.4 to 2.5. Lambs born after the transfer of fertilized eggs (all Fingalway) to Finnish Landrace, Galway and Fingalway ewes were also studied. There was evidence for a significant positive effect of selection for litter size within the Galway breed on plasma LH at 8 weeks of age. Finnish Landrace lambs had significantly higher levels of plasma LH at 8 weeks of age than did Galway Control lambs. These two groups did not differ with respect to plasma LH at 4 weeks of age. Non-additive genetic effects were significant at 4 weeks of age. The ranking of genetic groups on plasma LH was not consistent with their ranking for litter size. There was no evidence for a maternal effect associated with breed of dam on plasma LH and the effects of litter size were generally insignificant. Female lambs had significantly higher levels of LH at 4 weeks of age but there was no sex difference at 8 weeks because LH levels in males had increased. The correlation between the level of plasma LH at 4 and 8 weeks of age was -0.04. It is concluded that plasma LH is unlikely to prove a practical aid to selection for increased fecundity in sheep.

Dynamics of serum immunoglobulin concentrations in sheep during pregnancy and lactation

Monospecific antisera were used to measure the serum IgM1, IgG2 and IgM concentrations in pregnant an d non-pregnant ewes, rams and lambs over a period of eight months. The decrease of IgG1 and IgM concentrations which took place in ewes' serum at lambing was followed by a long and slow recovery phase (five to six months) during and after lactation, while no significant changes occurred in IgG2 concentrations. Serum immunoglobulin concentrations measured in a similar group of non-pregnant ewes throughout the same period showed no seasonal influence. Lambs' sera at three days after birth contained all three immunoglobulin classes and subclasses measured. There was no evidence of IgG2 deficiency. No sex differences were observed in immunoglobulin concentrations in lambs of all ages. Significant negative correlations were found between growth rate from six to 12 weeks and the IgG1 and IgG2 concentrations at 14 weeks.

A note on immunoglobulin concentrations in Scottish Blackface lambs born to 1- or 2-yr-old ewes

SUMMARYThe concentrations of maternal immunoglobulin in 2-day-old lambs born to Scottish Blackface ewes which had been mated when 6 to 7 mo old were significantly lower than in lambs born to these ewes a year later. But the mortality rates were almost identical. The concentrations in lambs born to the same ewes in successive years were significantly more highly correlated than the concentrations in lambs born to older females in successive years, examined in a previous study.

Variations in immunoglobulin concentrations in Merino and Scottish Blackface lambs

SUMMARYThe concentrations of maternal immunoglobulin in 2-day-old lambs varied widely. They were significantly correlated with the lengths of pregnancy and the serum protein concentrations of the adult female sheep (ewes), but not with the colostrum immunoglobulin concentrations, nor with the weights or ratios of weights of the lambs and ewes. The mean concentrations were as high in Merino as in Blackface lambs.Although there was some evidence that colostrum production was higher in ewes with twins than in ewes with single lambs, the immunoglobulin concentrations in the lambs fell significantly as litter size increased. They were significantly higher in male than in female twins, and in twins from litters containing both sexes than in twins from litters of one sex, but the difference between single males and females was not significant. Nor was the difference between the first and second born of each pair of twins. Twins and triplets born to ewes aged 7 years or more had particularly low concentrations. No other effects of the age of the ewe were found. The concentrations fell significantly as the date of lambing during the season advanced, and there were significant annual variations which could not be attributed to the weather. The correlation coefficients for the concentrations in lambs born to the same ewe in successive years were 0·309 and 0·298 (P < 0·001), respectively, for Merino and Blackface lambs.The mean concentration in lambs which died subsequently from infections was significantly lower than in the surviving lambs, but many lambs with very low concentrations survived.

Blood Glucose and Fructose in the Newborn Ruminant

Concentrations of blood glucose and fructose were studied in 8 calves and 20 lambs. Calves were removed from their dams immediately following birth. Jugular blood samples were taken 3min after birth and at 30min intervals until calves were 6h of age and then at 1h intervals until 24h of age. Calves were fed 1kg of their dam's colostrum at 6, 12, and 18h of age. Rectal temperatures were recorded at the same intervals as blood samples were taken. Jugular blood samples were taken from lambs within 3min after birth and at 2, 4, 6, 8, and 24h of age. Lambs were allowed to nurse their dams after the initial blood sample. Blood glucose averaged 62 mg/100 ml and fructose 52 mg/100ml in calves at birth while lambs had 13 mg/100ml glucose and 46 mg/100ml fructose at birth. Blood glucose and fructose decreased rapidly during the first few hours of life in calves. Feeding colostrum to calves did not give a uniform rise in blood glucose. Peak blood glucose occurred after the second feeding of colostrum. Body temperature remained normal throughout the 24h. Lambs exhibited low blood glucose through the first 24h of life. Blood fructose concentrations in lambs were similar to those of calves. Newborn neonatal ruminants may not be dependent upon glucose as their principle energy substrate during the first 24h of life.

Intravenous energy infusion in lambs: effects on nitrogen retentin, plasma free amino acids and plasma urea nitrogen

1. Acetate, propionate, butyrate and glucose were each administered intravenously (2.09 MJ (0.5 Mcal)/d) to lambs on either high-concentrate (HC) or high-roughage (HR) diets in two experiments with 4 × 4 Latin square design. During a control period all animals received a saline infusion.2. In lambs on the HC diet glucose was the most effective metabolite tested for improving nitrogen retention. Acetate was 51%, butyrate, 75%, propionate, 90% as effective as glucose in promoting N retention. Propionate infusion was most effective in increasing N retention in lambs on the HR diet. Acetate was 60%, butyrate, 75%, and glucose, 80% as effective as propionate. Glucose infusion did not lower plasma urea N (PUN) concentration in lambs receiving the HC diet, but the three volatile fatty acids (VFA) did lower it (P< 0.01). All energy sources significantly reduced the PUN concentrations with the HR diet, but differences between sources were not significant.3. Plasma concentrations of valine, isoleucine, leucine and phenylalanine were depressed to 57, 71, 89 and 90% of their control values during glucose, propionate, butyrate and acetate infusion. Plasma concentrations of lysine and methionine were significantly decreased from control values (P< 0.05) but there was no significant difference between energy sources. Lysine, valine, isoleucine and leucine were significantly (P< 0.01) higher in lambs given the HR diet than in lambs given the HC diet. The concentration of alanine was greater (P< 0.05) during glucose infusion than during acetate and butyrate infusions, indicating net synthesis of alanine and possibly other non-essential amino acids during glucose infusion, since the plasma free amino acid N concentration increased despite decreased concentrations of plasma essential amino acids during glucose infusion.4. The results indicated that glucose and propionate were superior to acetate and butyrate as energy sources for protein formation.5. The poor relationship between PUN and N balance and plasma free essential amino acids suggested that PUN concentration may have been inappropriate to assess the protein status under some dietary conditions.

Effect of Feed Consumption on Plasma Amino Acid Concentrations in Lambs

Increased consumption of a corn-soybean meal diet from maintenance through increments to approximately 2.5 times maintenance increased weight gain, gain :feed, plasma urea-nitrogen, and concentrations of most plasma free-amino acids. The failure of plasma sulfur-containing amino acids and histidine to increase with increased diet consumption may indicate that these amino acids were limiting performance. Since it influences plasma amino acid concentrations, feed intake is a major factor in interpretation of plasma amino acid data.