Assessment of the ovine acute phase response and hepatic gene expression in response to Escherichia coli endotoxin

Lipopolysaccharide (LPS), a bacterial membrane endotoxin, induces a systemic inflammatory response (IFR) through the activation of blood monocytes and hepatic kupffer cells. These cells secrete pro-inflammatory cytokines, which subsequently activate the hypothalamic-pituitary-adrenal axis (HPAA) to release cortisol, an anti-inflammatory hormone that regulates the IFR and subsequent immune response (IR). The intent of this study was to characterize the acute phase response in female sheep challenged systemically with a range of doses of Escherichia coli endotoxin. Yearling ewes were challenged with an i.v. bolus dose of LPS (0, 200, 400, 600 ng/kg BW) and the acute phase response assessed by measuring serum interleukin (IL)-6 and cortisol concentrations, and the febrile response over time. A follow-up liver biopsy study was performed to determine kinetic differences in the expression of eight candidate hepatic genes between LPS dose groups using real-time RT-PCR. The initial time trail did not follow a linear dose response relationship with respect to the febrile and HPAA response to LPS challenge. Serum IL-6 concentrations increased in the two highest treatment groups but did not correlate with the observed febrile and HPAA response. The expression of Toll-like receptor 4, CD14, IL-6, tumor necrosis factor-alpha, IL-1beta, macrophage migration inhibitory factor, 11-beta-hydroxysteroid dehydrogenase (HSD), and tachykinin precursor 1 hepatic genes was dependent on both the dose and the kinetics of the response to LPS.     

Activation of the ovine hypothalamic-pituitary-adrenal axis and febrile response by interleukin-6: A comparative study with bacterial lipopolysaccharide endotoxin

Sheep were subjected to immune challenge with either recombinant human interleukin-6 (rhIL-6; 2.0 μg/kg; n = 5), Escherichia coli lipopolysaccharide (LPS) endotoxin (400 ng/kg; n = 7), or saline (n = 6) to determine if IL-6 activates the febrile and hypothalamic-pituitary-adrenal axis (HPAA) responses in sheep, and to compare these responses with those associated with endotoxemia. Blood was collected over time to measure plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations as indicators of HPAA activity. Unlike LPS, rhIL-6 was not pyrogenic in sheep at this challenge dose. In contrast, rhIL-6 elicited ACTH and cortisol responses that peaked earlier than those induced by LPS. These results suggest that this dose of IL-6, alone, is not sufficient to elicit the febrile response in sheep, however, it is a potent activator of the ovine HPAA response.     

Pharmacokinetics of penicillin-G in ewes and cows in late pregnancy and in early lactation

Concentrations of penicillin-G in serum were determined after single intravenous doses of potassium penicillin-G (10 mg/kg body wt) to ewes and cows in late pregnancy and in early lactation. Penicillin-G in serum was analysed by a microbiological method and pharmacokinetic parameters were calculated by model-independent methods. Serum concentrations were lower in early lactation than in late pregnancy in both ewes and cows. The differences were statistically significant at most sampling times in ewes but only during the first hour in cows.
Weight corrected values of clearance and volume of distribution were significantly higher in early lactation than in late pregnancy in both ewes and cows. Mean residence time and elimination-half life were shorter in lactating than in pregnant ewes, however for the latter parameter the difference was not statistically significant. Neither of these parameters changed in cows.
It is concluded that in both ewes and cows pharmacokinetic parameters of penicillin-G are altered from late pregnancy to early lactation but that these changes have little practical impact and do not call for a revised dosage regime of the studied drug.     

Influence of reproductive state on pituitary-adrenal activity in the ewe.

Plasma corticosteroid concentrations are altered in pregnancy, during the reproductive cycle and by ovariectomy in many species. This study was designed to examine basal ACTH and cortisol in ewes of four different reproductive statuses: ovariectomized, nonpregnant cycling, nonpregnant noncycling, and pregnant. Blood samples were drawn every 4 hr for 48 hr from ewes during quiet, undisturbed conditions and analyzed for plasma ACTH, cortisol and progesterone concentrations. There were no significant changes in ACTH, cortisol or progesterone over time. Mean progesterone concentrations were significantly greater in the pregnant ewes than in all other ewes, and were greater in cycling ewes than noncycling or ovariectomized ewes. Mean ACTH was significantly greater in pregnant ewes than noncycling ewes, and mean cortisol was significantly greater in cycling ewes than in nonpregnant cycling or noncycling ewes. Ovariectomized ewes also had significantly greater mean cortisol concentrations than cycling ewes. The results demonstrate that there is an increase in basal ACTH and cortisol in ovine pregnancy.     

Glucose homeostasis and metabolic adaptation in the pregnant and lactating sheep are affected by the level of nutrition previously provided during her late fetal life

This study investigated whether undernutrition (UN) during late fetal life can programme the subsequent adult life adaptation of glucose homeostasis and metabolism during pregnancy and lactation. Twenty-four primiparous experimental ewes were used. Twelve had been exposed to a prenatal NORM level of nutrition (maternal diet 15 MJ ME/d) and 12 to a LOW level of nutrition (maternal diet 7 MJ ME/d) during the last 6 weeks pre-partum. The experimental ewes were subjected to two intravenous glucose tolerance tests (IGTT) in late gestation (one prior to (G-IGTT) and one by the end of a feed restriction period (RG-IGTT)), and a third around peak lactation (L-IGTT). LOW had lower basal insulin concentrations during lactation, and significantly decreased absolute insulin secretion during the L-IGTT in spite of similar glucose tolerance, indicating increased insulin sensitivity in LOW during lactation. There was no effect of prenatal UN on glucose tolerance during G-IGTT, however, during RG-IGTT LOW was more glucose intolerant and apparently more insulin resistant compared to NORM. In conclusion, UN during late fetal life in sheep impairs subsequent pancreatic insulin secretory capacity during adult life, and reduces plasticity of down-regulation of insulin secretion in response to a metabolic challenge. Furthermore, prenatal UN appears to programme mechanisms, which in young adult females can shift the insulin hypersensitivity observed during early lactation into an insulin resistance observed during late gestation and feed restriction. Early postnatal UN caused by lowered milk intake in early postnatal life may have contributed to these phenomena.     

Thermogenesis, blood metabolites and hormones, and growth of lambs born to ewes supplemented with algae-derived docosahexaenoic acid

Neonatal lamb mortality is a major factor affecting profitability in the sheep industry, and lamb thermogenesis is a key element in neonatal lamb survival. Increased lamb vigor has been reported when ewes were supplemented during late gestation with algae-derived docosahexaenoic acid (DHA); however, the effects of DHA on lamb thermogenesis and immunocompetence have not been investigated. Eighty twin-bearing Targhee ewes (ages 2 to 5 yr; 68.5 ± 3 kg) were assigned randomly to 1 of 2 supplement treatments to determine the effects of feeding DHA to ewes during late gestation and early lactation on lamb thermogenesis, serum metabolites and hormones, and lamb growth. Supplement treatments were 12 g·ewe(-1)·d(-1) of algae-derived DHA (DHA Gold Advanced Bionutrition Corp., Columbia, MD; algae-derived DHA); and no algae-derived DHA (control). Supplements were individually fed daily during the last 30 d (±7 d) of gestation and pen fed (6 pens/treatment with 6 or 7 ewes/pen) during the first 38 d (±7 d) of lactation. One hour after lambing and before nursing, twin-born lambs were weighed, blood sampled via jugular puncture, and placed in a dry cold chamber for 30 min (0°C), and rectal temperatures were recorded every minute for 30 min. Lambs were removed from the cold chamber, blood sampled, warmed for 15 min, and returned to their dam. Ewes were blood sampled, and colostrum samples were collected 1 h postpartum. Ewe and lamb sera were assayed for glucose, NEFA, cortisol, and leptin. Lamb rectal temperature, glucose, NEFA, cortisol, leptin, and birth weights did not differ between treatments. The BW at 38 d was greater (P = 0.03) for lambs born to control ewes than for lambs born to algae-derived DHA-supplemented ewes; however, the colostrum of algae-derived DHA-supplemented ewes had a greater specific gravity (P = 0.05) than for control ewes. Overall, despite a potentially positive effect on ewe colostral IgG concentrations, supplementation of algae-derived DHA during late gestation and early lactation had a negative effect on lamb BW and did not affect indices of lamb thermogenesis.     

Maternal leptin is elevated during pregnancy in sheep

Maternal plasma leptin is elevated during pregnancy in several species, but it is unclear to what extent this elevation reflects changes in adiposity or energy balance. Therefore, Karakul ewes (n = 8) were fed to minimize changes in maternal energy status over the pregnancy-lactation cycle. They were studied 20-40 d before breeding and during mid pregnancy (d 50-60 post coitus [PC]), late pregnancy (d 125-135 PC) and early lactation (d 15-22 post partum). Consistent with the maintenance of near energy equilibrium in nongravid maternal tissues, maternal body weight was increased only during late pregnancy when the weight of the conceptus became significant and plasma concentrations of insulin, NEFA and glucose did not vary with physiological state. In contrast, maternal plasma leptin concentration rose from 5.3 to 9.5 ng/mL between prebreeding and mid pregnancy and then declined progressively through late pregnancy and early lactation. Leptin gene expression increased 2.3 fold in maternal white adipose tissue (WAT) from prebreeding to mid pregnancy and declined to prebreeding levels during early lactation. To determine whether tissue response to insulin was involved in this effect, insulin tolerance tests were performed. The maternal plasma glucose response declined from prebreeding to early lactation, but was not correlated with either plasma leptin concentration or WAT leptin mRNA abundance. In conclusion, pregnancy causes an increase in the synthesis of leptin in sheep. This stimulation does not require increases in adiposity or energy balance and is unrelated to the ability of insulin to promote glucose utilization.     

Acute-phase proteins,cortisol and haematological parameters in ewes during the periparturient period

Numerous subclinical diseases in sheep occur in the periparturient period and involve inflammatory processes; therefore, determining markers, such as acute-phase proteins (APPs), can allow an early diagnosis. Therefore, the objective of the present study was to assess changes in the plasma concentration of APPs and cortisol in clinically healthy ewes in the periparturient period for use in future studies. At the same time, haematological parameters were monitored. We showed that plasma APPs and cortisol concentrations were significantly higher in pregnant ewes than before insemination. A gradual increase in the SAA concentration was observed from the 14th day before to the day of parturition, while Hp was reduced from 2 weeks before up to 2 weeks after delivery. A significant increase in the Fb concentration was detected from the 14th day before to the 1st week after delivery. The cortisol concentration did not undergo significant changes in the periparturient period. We found an increase in the SAA and Fb concentrations and decrease in Hp in the periparturient period. The direction of the change in APPs of healthy ewes in the current study may be related to their distinct regulatory mechanisms during pregnancy. The APPs are usually altered during infection, inflammation, neoplasia, stress and trauma; therefore, knowing their reference values could help lead to an early diagnosis of subclinical forms of some diseases and pregnancy complications in ewes. The haematological analysis showed that ewes in late pregnancy and postpartum compared to dry period were under metabolic stress related to pregnancy and lactation.     

Antibody responses to bacterial antigens in the pregnant ewe

The humoral immune response to the novel antigen Brucella abortus (S19) was examined in nonpregnant ewes and in ewes at different stages of pregnancy. Both the primary and secondary responses were monitored, by measuring the levels of total antibody, Immunoglobulin G (IgG), and complement fixing antibody. Results showed that total antibody production was significantly (p<0.01) impaired in late pregnancy and that IgG titres persisted at significantly (p<0.05) higher levels in non-pregnant animals late in the primary response and following the booster inoculation. Complement fixing antibody levels were significantly higher in non-pregnant ewes and animals inoculated post-partum. These results suggest that active immunity can be altered during pregnancy, with qualitative changes in the class and biological activity of antibody.     

Oxidant and antioxidant profile of hyperketonemic ewes affected by pregnancy toxemia

Background: Negative energy balance during late pregnancy in ewes is an important cause of hyperketonemia. Ketone bodies can generate superoxide radicals and cause oxidative stress and cellular dysfunction, as noted in cows with subclinical ketosis or in diabetic people. Objective: The aim of this study was to evaluate the role of hyperketonemia in initiating the process of lipid peroxidation. Methods: The study included 10 pregnant ewes (aged 3.5–6 years) with pregnancy toxemia, 10 clinically healthy pregnant ewes, and 10 clinically healthy nonpregnant ewes. Serum concentrations of β‐hydroxybutyrate (BHB), cortisol, and glucose, plasma activities of glutathione peroxidase, superoxide dismutase, and catalase, and plasma concentrations of thiobarbituric acid reactive substances (TBARS), markers of lipid peroxidation, and reduced glutathione were measured. Data from the 3 groups were statistically analyzed and compared. Results: Serum concentrations of BHB, cortisol, and TBARS were significantly higher in ewes with pregnancy toxemia when compared with concentrations in healthy pregnant and nonpregnant groups (P≤.05). In ewes with pregnancy toxemia, a strong positive correlation was found between concentrations of TBARS and BHB (r=.80; P=.002) and between concentrations of BHB and cortisol (r=.76; P=.005). Conclusions: Oxidative stress and lipid peroxidation are involved in the development and complications of pregnancy toxemia. An association between hyperketonemia and the products of lipid peroxidation has also been demonstrated, suggesting that ketosis is a risk factor in the development of lipid peroxidation and oxidative stress in ewes affected by pregnancy toxemia.     

Regulation of adipose tissue metabolism during pregnancy and lactation in the ewe: the role of insulin

This study was conducted to examine the effect of insulin on lipid metabolism of adipocytes during pregnancy and lactation in ewes. During the first 3 mo of pregnancy, metabolism of adipocytes from omental adipose tissue was characterized by a high rate of de novo lipogenesis (90 to 125 nmol of acetate incorporated into lipids.2 h-1.10(6) cells-1) and a 38% reduction in response to beta-lipolytic stimulus (isoproterenol 10(-6) M). Simultaneously, there was a rise in the number of high-affinity insulin receptors (Kd = .2 nM), and insulin binding characteristics showed a decrease in the negative cooperativity phenomenon. Moreover, lipogenesis stimulated by insulin (1 mU/ml) increased in comparison with observations in nonpregnant ewes. The last third of pregnancy and early lactation were characterized by a marked fall in lipogenesis and a simultaneous increase in isoproterenol-stimulated lipolysis. During lactation, the number of total insulin receptors was decreased by 62% and insulin stimulation of lipogenesis became inefficient. Results suggest that insulin plays a direct role in adipose tissue metabolism during pregnancy.     

放牧绵羊微量元素摄入量与季节变化的关系研究

采用体质量-口罩法,分别在2、4、6、8、10、12月对天山北坡中段草地放牧的新疆细毛羊采食量进行测定,通过样方对牧草微量元素含量进行测定,计算放牧绵羊微量元素摄入量,另外不同季节绵羊发生周期性生理变化,对微量元素的需要量也不同,把不同季节放牧绵羊微量元素摄入量和需要量进行比较。研究结果得出不同季节绵羊从每天的采食中所获得的铁、锰、钴等微量元素能满足其需要。草地牧草中严重缺锌,母羊除在空怀期外其余时间锌缺乏量为16.0%82.2%,特别是在母羊泌乳前期只能从牧草中获得需要量17.8%的锌。绵羊怀孕后期和泌乳前期缺铜55%和59%,常年缺硒6%52%。     

The effect of pregnancy and lactation on digestive processes in sheep

The average passage time, the rumen fluid volume and the digestibility of the organic matter were determined in addition to 3 individual feeding experiments with fertility oriented crossbreed ewes, which received pelleted straw-concentrate mixtures. The average passage time of the feed particles through the digestive tract is shorter in pregnant animals than in lactating ones. It is longest in non-pregnant sheep. High quotas of straw and coarse particles prolong the passage time, increasing feed intake and supplements of long straw shorten it. The volume of rumen fluid is lower in ewes fed ad libitum in the stage of late pregnancy and after lactation than during lactation. The rumen fluid volume is also lower in restrictively fed animals during the stage of late pregnancy than during lactation. In animals in the stage of late pregnancy it correlates negatively with the weight of the litter. On an average of all experiments at maintenance level the digestibility of the organic matter in ewes in the 4th month of pregnancy gravidity amounted to 56.6%, in the 2nd month of lactation to 59.8% and in wethers to 59.5% Due to an increase of energy intake from maintenance to 2. maintenance digestibility of the straw-concentrate mixture with 40% straw decreased by 5.5 units and of that with 60% straw by 17.8 units in the period before delivery. Pregnancy in the 4th month resulted in a digestion depression of between 3.0 and 5.8 units.     

Seasonal variations in the gastro-intestinal nematode populations of Scottish hil sheep.

In each of two consecutive years, groups of breeding ewes were removed from a hill farm in the west of Scotland on four occasions, namely late pregnancy, early lactation, autumn and early winter. At slaughter the major nematode genus present in the alimentary tract was Ostertagia, with O circumcincta the predominant species but three species previously found in Scottish hill sheep, Bunostomum trigonocephalum, Strongyloides papillosis and Chabertia ovina were absent. An absolute increase in total nematode burden and faecal egg count was apparent in the ewes commencing in late pregnancy, reaching a maximum during lactation and falling again in autumn and early winter. This peri-parturient increase in the nematode population could not be solely attributed to the maturation of previously inhibited larval stages but was primarily the result of the development of recently ingested infection; the latter situation thought to be due to a temporary relaxation of immunological response by the ewe at parturition or early lactation. Serum pepsinogen values in ewes remained elevated throughout the grazing season and were always higher than those of their lambs, suggesting that the ewe, although allowing few parasites to become established, was under considerable challenge in the autumn. The worm burdens of the lambs were always low in autumn and early winter with Ostertagia spp being the major genus present during the autumn and Trichostrongylus spp being the predominant genus during the early winter.     

Digesta kinetics, ruminal fermentation characteristics and serum metabolites of pregnant and lactating ewes fed chopped alfalfa hay

Eight ruminally cannulated ewes (four control and four bred; average BW = 85.7 kg), limit-fed alfalfa hay (1.86% BW), were used in two experiments to determine the effects of pregnancy and lactation on digestive function and serum metabolites. Seven-day sampling periods were used starting on d 102, 118 and 132 of gestation (Exp. 1) and d 14 and 32 of lactation (Exp. 2). Particulate (6.8 vs 4.9%/h; PPR) and fluid passage rates (13.9 vs 10.9%/h) were greater (P less than .05) and gastrointestinal mean retention time (28.9 vs 35.7 h) and fluid turnover time (FTT, 7.5 vs 9.5 h) were lesser (P less than .05) in pregnant than in nonpregnant ewes, respectively. Isobutyrate concentration was lower (P less than .05) in pregnant (1.7 mol/100 mol) than in nonpregnant (1.9 mol/100 mol) ewes. No differences (P greater than .10) were noted for any other ruminal fermentation measures between pregnant and nonpregnant ewes. In Exp. 2, no differences (P greater than .10) were noted in digesta kinetics or ruminal fermentation measures except for isobutyrate and isovalerate molar proportions and serum urea N (SUN) concentration. Isobutyrate, isovalerate and SUN concentrations (21.8 vs 26.1 mg/dl) were lower (P less than .05) in lactating ewes than in nonlactating ewes. Gastrointestinal fill (5.7 vs 7.7 g/kg BW) and FTT (9.3 vs 12.7 h) were lesser and DM digestion (66.7 vs 57.4%) was greater (P less than .05) in lactating than in nonlactating ewes. Data suggest that, during pregnancy, passage rate increases occur without affecting DM digestion and that, during lactation, PPR is not affected when ewes are limit-fed.     

Pancreatic insulin release and peripheral insulin sensitivity in German black headed mutton and Finish Landrace ewes: evaluation of the role of insulin resistance in the susceptibility to ovine pregnancy toxemia

German black headed mutton (GBM) ewes are recognized as being highly susceptible to ovine pregnancy toxemia (OPT). The present trial was performed to evaluate whether a breed-dependent gestational diabetes mellitus-like insulin resistance during late pregnancy might be responsible for the high incidence of OPT in the GBM breed. Modified frequently sampled intravenous glucose tolerance tests (300 mg glucose and 0.03 IU insulin per kg of BW) were performed during mid and late pregnancy, the periparturient, and the dry period in polytocous 3.5-yr-old GBM and Finnish Landrace (FL) ewes fed according to their requirements. The corresponding blood samples were analyzed for plasma concentrations of glucose, insulin, nonesterified fatty acids (NEFAs) and β-hydroxybutyrate (β-HB). In addition, the baseline plasma cortisol concentrations were determined during late pregnancy. The BW gain during pregnancy and the rearing success did not differ between the GBM and FL ewes. In both breeds, late pregnancy was associated with decreased basal plasma glucose concentrations and enhanced glucose disposal, as well as elevated baseline β-HB values. Only in the GBM ewes did the plasma NEFA concentrations increase significantly during advancing pregnancy. Moreover, significantly higher baseline plasma NEFA concentrations as well as lower (P < 0.05) basal plasma glucose values were recorded during late pregnancy in the GBM than in the FL ewes. The first-phase insulin secretion, the peripheral insulin sensitivity, and the baseline plasma cortisol values did not differ between both breeds during late pregnancy. It is concluded that increased lipolysis during late pregnancy is a characteristic of the GBM breed. Moreover, elevated plasma NEFA concentrations may contribute to impaired pancreatic insulin response and peripheral insulin resistance in GBM ewes and thus promote OPT.     

Insulin responsiveness to glucose and tissue responsiveness to insulin in lactating, pregnant, and nonpregnant, nonlactating beef cows

Insulin responsiveness to glucose and tissue responsiveness to insulin, using the hyperglycemic clamp and the hyperinsulinemic euglycemic clamp techniques, were measured in lactating, late pregnant, and nonpregnant, nonlactating (NPNL) beef cows. The glucose infusion rate (GIR) in the hyperglycemic clamp technique was higher (P less than .05). in lactating cows than in NPNL cows. The plateau in plasma insulin concentration (insulin responsiveness) was higher (P less than .05) in lactating cows than in late pregnant and NPNL cows. Pregnant cows tended to have higher GIR and lower plateau in plasma insulin concentration than NPNL cows. In the hyperinsulinemic euglycemic clamp technique, GIR (tissue responsiveness to insulin) was higher (P less than .05) in lactating cows than in late pregnant cows; values for NPNL cows were intermediate. We conclude that insulin responsiveness to glucose and tissue responsiveness to insulin were enhanced during lactation but tended to be decreased during late pregnancy in beef cows.     

Humoral immunity in the ewe. 2. The effect of pregnancy on the primary and secondary antibody response to protein antigen

This study examines the effect of pregnancy on the quantity and isotype of antibody in ewes immunised with a novel primary antigen. The primary and secondary antibody levels to bovine serum albumin (BSA) in alum adjuvant, were compared between non-pregnant ewes and ewes immunised at different stages of pregnancy. Anti-BSA isotype specific responses were measured using an indirect ELISA. Results show the levels of immunoglobulin M (IgM) increased and persisted in response to BSA during pregnancy (P less than 0.05). Secondary immunoglobulin G1 (IgG1) titres were significantly impaired in late pregnancy and during lactation (P less than 0.05). The lower levels of immunoglobulin G2 (IgG2) were unaffected by pregnancy under these experimental conditions. Ewes were also immunised with BSA in alum adjuvant for their primary inoculum and BSA in different adjuvants for the secondary inoculation. Primary IgM persisted at higher levels during pregnancy compared with the response in non-pregnant ewes (P less than 0.05). Following the secondary injection, lower levels of anti-BSA specific IgM, IgG1 and IgG2 antibodies were produced in late pregnancy and during lactation compared with the levels in non-pregnant control ewes (P less than 0.05). Alterations in regulatory T-cell function or effector B-cell activity would most readily explain the qualitative changes in antibody titre observed following primary injection during pregnancy. The results also suggest an associated impairment of immunological memory following primary immunisation during pregnancy.     

Duration of anestrus in Pramenka and Romanov ewes in Yugoslavia.

Jugular plasma progesterone was determined for two groups of native Yugoslavian ewes (Pramenka, Groups 1 and 2) and for a group of Romanov ewes (Group 3) from the end of January to late October in 1988. Ewes were pregnant until the end of March (pregnancy progesterone concentrations, 2.84 to 33 ng/mL). From the end of March to the beginning of July, progesterone concentration decreased (0 to .15 ng/mL). From early July to late October, progesterone concentrations increased. Progesterone concentrations were at their nadir near the summer solstice and increased significantly by early July in all three groups. The duration of anestrus was similar in Pramenka and Romanov ewes. In nonpregnant Pramenka ewes, the pattern of changes in plasma progesterone was similar to those seen in pregnant ewes except for an earlier decline with very low concentrations observed after mid-March.     

Effects of Level and Distribution of Concentrate in Late Pregnancy on Ewe and Lamb Performance

Abstract

During two different years, 1986 and 1989, 129 and 102 ewes, respectively, were used to compare the effects of level and feeding pattern of concentrate during the last eight weeks of pregnancy. The ewes were given hay to cover maintenance, with supplemental feeding for pregnancy based on different amounts of concentrate. The control groups were fed according to Swedish recommendations, totalling 20 kg of concentrate, maximum level 0.4 kg per ewe and day (20:0.4) in a two-level pattern. The experimental groups were fed 20:0.7, 24:07 or 30:1.0 with a gradually rising feeding pattern. The treatments had a significant effect on changes in the live weight of ewes during late pregnancy and early lactation, with ewes on higher feeding levels losing less weight during pregnancy and gaining less weight on pasture. Over the whole production year, the changes during different production periods levelled out the total effect. Late pregnancy feeding also had a significant effect on lamb growth, with lambs from ewes fed on the highest feeding level growing significantly better. Lambs from ewes fed on a gradually rising feeding pattern showed significantly better growth in Expt. 1 but not in Expt. 2.