In a 2 × 3 factorial arrangement, 3 levels of L-arginine (0, 75 and 150 mg/kg BW per day) were tested at two stages of pregnancy (Early 60 days vs. Late 60 days) on the maternal blood metabolites and postnatal milk composition relative to the newborn traits of Najdi ewes. Thirty adult pregnant Najdi ewes were randomly assigned into 6 treatments (n = 5). Control early (CE) ewes were orally administered 50 mL normal saline (0.9% NaCl) daily during the first 60 days of pregnancy; control late (CL) ewes were similar to CE except saline was given at the last 60 days of pregnancy; low dose of L-arginine at early pregnancy (LE); low dose of L-arginine at late pregnancy (LL); high dose of L-arginine at early (HE) and high dose of L-arginine at late pregnancy (HL). Blood and milk samples were collected on a weekly basis. Data of lambing and newborn traits were considered. There were non-significant differences in litter size due to L-arginine; however lamb birth and weaning weights increased by 35% in LE-ewes. Arginine did not change blood protein and albumin. Low arginine decreased lipid fractions, creatinine, urea, and milk fat; however, it increased AST, ALT, milk lactose and milk ash. Administration of L-arginine at 75 mg/Kg BW per day for 60 days at an early gestation in ewes improved the maternal body health and milk composition for the welfare of the neonates.
Najdi ewes represent a valuable sheep population in the Kingdom of Saudi Arabia. However, these animals are bred under hot climates, sandstorms, lack of fresh water and scarcity of green forages resulting in reduced productivity and profitability. Several studies have been focusing on the roles of essential and nonessential amino acids on animal growth, development, reproduction, production, and health wellbeing aspects [
This study has been conducted during September 2017 and June 2018. Pregnant Najdi ewes at their first to third parity with age of 12 - 30 month and weight of 40 - 60 kg (average 51.4 ± 8.7 kg) were reared in the same breeding farm, tested to be free from mandatory reportable diseases and located in animal production research unit, Agricultural experimental station, Qassim University, Kingdom of Saudi Arabia. Ewes were maintained in semi shaded pens, offered 300 g barley/head/day as a concentrate in addition to alfalfa hay ad lib according to NRC requirements [
Thirty adult pregnant Najdi ewes were randomly assigned into six groups (n = 5 ewes/group) as follow; first group (CE) was defined as control early pregnancy in which ewes were at their early (first 60 days post breeding) stage of pregnancy and given orally daily 50 ml normal saline (0.9% NaCl), second group (CL) ewes were in late (last 60 days) pregnancy stage and orally administered 50 ml normal saline daily until parturition, third group (LE) ewes were given daily low dose of L-arginine [Herbstore, Diamond Bar, CA USA (75 mg/kg B.W/day)] during the first 60 days of pregnancy, group four (LL) ewes were given daily similar dose of group 3 during their last 60 days of gestation, group five (HE) ewes were given daily high dose of L-arginine (150 mg/kg B.W/day) during the early 60 days of pregnancy and group six (HL) ewes were given similar dose to group five during their last 60 days of pregnancy.
Blood samples for plasma were collected via the jugular vein in heparinized Vacutainer® tubes (Becton Dickinson, Oxford, UK). Sampling just started before the commencement of the treatment (d = 0) and proceeded once per a week until parturition in the late pregnant groups, however in the early pregnant ewes, blood samples were collected once per a week during treatment period and proceeded in a once per month thereafter until parturition. Plasma was separated immediately after blood collection by centrifugation (1500 × g for 15 min/5˚C), harvested, aliquot and stored at −20˚C until analysis. Blood biochemical constituents were determined by commercial reagents (Human Gesellschaft für Biochemica und Diagnostica mbH, Germany). Total protein was determined according to Weichselbaum [
Milk samples were collected in clean tubes containing potassium dichromate (0.1 ml, 0.3%). Sampling started soon after the end of colostrum and once per a week until weaning at two months of neonate age. Milk samples were kept in the fridge (5˚C) until proximate analysis was performed. Milk samples were analyzed using FUNK GERBER (Lactostar, Germany) milk analyzer according to the AOAC [
Offspring were weighed at birth and at weaning (day 60) using a scale balance. Also percentage of survival at birth and weaning were recorded within each treatment.
All variables data were analyzed by the least square analysis of variances for repeated measures procedure of SAS [
As depicted in
fetus, however giving a high dose (150 mg/kg B.W) at late gestation was not as effective in this respect as when given at early gestation. The heaviest (P < 0.05) lamb weaning weight at 60 days age (
The highest (P < 0.05) lamb growth rate (
As pregnancy advances, plasma protein (
(LL; 2.28 g/dl), representing +54% above control (
Generally, L-arginine diminished (P < 0.01) blood cholesterol compared with control (
0.05) blood cholesterol by 21% compared with control figures, however high arginine slightly (P > 0.05) reduced this value by barely 9%. Administration of either dose of L-arginine at early gestation reduced (P < 0.05) triglycerides (TG) by 30% - 41.5% of the control value (
As shown in
In the ordinary circumstances (i.e. control) urea profile (
Administration of the high dose of L-arginine increased (P < 0.01) maternal blood urea at either stage by 13% - 19%. Reversibly, giving the low dose (LE &LL) of L-arginine not only maintained urea at its basic levels, but it also normalized the blood urea concentrations throughout pregnancy.
Administration of L-arginine significantly (P < 0.01) increased AST activity (
of ALT throughout pregnancy (
The increase in birth weight in the treated ewes might be ascribed to the anabolic effects of L arginine due to its angiogenic effect on the placental blood vessels. The low dosage of arginine given at early gestation resulted in the best birth (4.99 kg) and weaning (18.4 kg) weights. During early days of pregnancy the mothers require protein as a signal for the maternal recognition of pregnancy [
Milk constituent % | Treatment | |||||
---|---|---|---|---|---|---|
Control Early | Control Late | Low Arg. Early | Low Arg. Late | High Arg. Early | High Arg. Late | |
Moisture | 85.21 ± 1.11a* | 81.44 ± 0.67c | 81.82 ± 1.26bc | 82.24 ± 1.20bc | 84.59 ± 0.61ab | 83.06 ± 0.56abc |
Total Solids | 14.81 ± 1.11c | 18.56 ± 0.67a | 18.18 ± 1.26ab | 17.76 ± 1.20ab | 15.41 ± 0.61bc | 16.94 ± 0.56abc |
Fat | 7.27 ± 0.65bc | 9.30 ± 0.62a | 9.11 ± 0.84ab | 7.83 ± 0.66abc | 6.55 ± 0.28c | 7.51 ± 0.40abc |
Solids Non Fat | 7.54 ± 0.53b | 9.25 ± 0.47a | 9.07 ± 0.52a | 9.93 ± 0.64a | 8.86 ± 0.40ab | 9.43 ± 0.40a |
Lactose | 2.70 ± 0.44b | 3.97 ± 0.35a | 3.53 ± 0.28ab | 3.98 ± 0.37a | 2.80 ± 0.27b | 4.24 ± 0.22a |
Protein | 3.99 ± 0.20b | 4.50 ± 0.35a | 4.73 ± 0.45a | 5.08 ± 0.37a | 5.11 ± 0.41a | 4.27 ± 0.36ab |
Ash | 0.84 ± 0.03cd | 0.79 ± 0.02d | 0.81 ± 0.03cd | 0.87 ± 0.02bc | 0.94 ± 0.02a | 0.92 ± 0.01ab |
*a,b,c,dMeans in the same row with different superscripts significantly (P < 0.05) differ. CE = Saline at early pregnancy, CL = Saline at late pregnancy, LE = 75 mg/kg BW at early pregnancy, LL = 75 mg/kg BW at late pregnancy, HE = 150 mg/kg BW at early pregnancy, HL = 150 mg/kg BW at late pregnancy.
such a dose on the maternal tissues and its udder.
The congested teats impeded the natural suckling of the neonates resulting in a high percent of mortality. Overall, the best treatment in milk yield (visual observation, not determined) and composition was found in LE-ewes resulting in the heaviest lamb weaning weights. Arginine serves as a common precursor for the synthesis of NO (a vasodilator and a signaling molecule) and polyamines (key regulators of DNA and protein synthesis) that are crucial for placental angiogenesis and growth in mammals [
The lowering effect of L-arginine on blood lipid fractions, in the current study agrees with a previous study [
The dosage and duration of administration of L-arginine must be considered when designing an experiment to test its effect on cell biology. Moreover, type of animals (i.e. monogastrics vs. ruminants) is of great concern with respect of timing and duration of administration. Drenching pregnant ewes at their early (~first 60 days post breeding) gestation with a daily dose of 75 mg L-arginine per kilogram body weight would be a beneficial approach to obtain heavy and healthy offspring and maintain the maternal health wellbeing. Moreover, this study must be furthered by using larger numbers of animals and also to quantitate the milk yield and its chemical composition and correlate such traits with neonatal survival and growth.
The authors acknowledge Qassim University for providing the lodging for animals, and the farm crew for their assistance throughout the experiment.
This study was approved by the Animal Care and Welfare Committee, Deanship of Scientific Research, Qassim University, Kingdom of Saudi Arabia.
The authors declare no conflicts of interest regarding the publication of this paper.
Zeitoun, M.M., Al-Ghoneim, A.A., Al-Sobayil, K.A., Hassanein, Y.R., Mansour, M.M., El-Azrak, K.E.-D.M., Attia, M.F.A. and Almundarij, T.I. (2019) L-Arginine Supplementation Alters Maternal Blood Biochemical Attributes and Milk Composition Relative to Neonatal Traits of Najdi Ewes. Open Journal of Animal Sciences, 9, 341-354. https://doi.org/10.4236/ojas.2019.93028