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Simple Summary: Improvement of fetal growth in twin pregnancies is one of the major goals of extensive sheep production systems, as lambs' birth weight is correlated with their survival. This is especially relevant in harsh environments where natural maternal nutrient restriction is common. Maternal arginine (Arg) supplementation improves fetal growth, but Arg is degraded in the rumen, has a short biological half-life, and the high cost of protected forms limits its use in extensive sheep systems. N-carbamylglutamate (NCG) is not degraded in the rumen, increases arginine synthesis, and improves urea recycling, suggesting it may be an option as an alternative to Arg. The aim of this study was to evaluate the effect of oral NCG supplementation from 100 days of gestation (dga) to term in naturally nutrient-restricted grazing twin-bearing ewes, on maternal, placental, and fetal variables. The serum concentrations of NCG were increased 15-fold, and the plasma urea, albumin and phosphorus concentrations were reduced in supplemented ewes compared to controls, but there was no major effect on the dam or fetal body or organ weights nor the antioxidant markers and other blood biochemical parameters. These results indicate that NCG supplementation in mid-to-late gestation in grazing ewes was unable to rescue the negative production effects of severe natural nutritional restriction on both the dam and fetuses. The challenge of meeting the nutrient requirements of pregnant ewes in harsh environmental conditions reinforces the need for future research to identify novel strategies to improve lamb survival in such environments around the world. N-carbamylglutamate (NCG) is postulated to improve fetal growth in nutrient-restricted gestations when supplemented from day 35 to 110 of gestation, but the effects of supplementation from 100 days of gestation to birth have not been evaluated. The aim of this study was to evaluate the effect of oral NCG supplementation from 100 days of gestation (dga) to term in naturally nutrient-restricted grazing twin-bearing ewes, on the maternal body weight (BW), body condition score (BCS), placental morphology, fetal body and organ weights and blood biochemistry and antioxidant status in the ewe and fetuses. Eighteen twin-bearing ewes maintained under grazing management were randomly allocated to either a treatment group (NCG; n = 10), orally dosed once daily with 60 mg/kg of NCG from day 100 until 140 dga, or an unsupplemented control group (CON; n = 8). At 140 dga, blood gases, redox status, maternal and fetal plasma and fetal biometrics were obtained after caesarian section. The serum concentration of NCG was increased 15-fold in the NCG ewes compared to the CON. No major effects on dam or fetal body weight nor on blood biochemistry or antioxidant parameters were observed. These results indicate that NCG supplementation in mid-to-late gestation to grazing ewes was unable to rescue the negative production effects of severe natural nutritional restriction on both the dam and fetuses. [ABSTRACT FROM AUTHOR]

Maternal nutrient restriction in twin- bearing ewes reduces the colostrum protein content, resulting in reduced postnatal growth and greater lamb mortality in twin- compared with single-bearing ewes. N-carbamylglutamate (NCG), an analogue of N-acetylglutamate increases endogenous arginine syn- thesis and is postulated to influence fetal growth and development and potentially lamb survival. The effect of maternal supplementation with NCG in mid-late gestation on colostrum quality and nutrient status of nutrient-restricted ewes has not been reported. The aim of this study was to evaluate the effect of oral maternal supplementation with NCG during mid–late gestation in nutrient restricted twin-bearing ewes on maternal body weight (BW) gain, body condition score (BCS), nutritional status and colostrum composition. Twin- bearing ewes (n = 20), managed in individual pens, were orally dosed once-daily with 60 mg/kg BW NCG in a water carrier from 100 d of gestation (dg) to lambing and were compared with unsupplemented controls (CON; n = 21). The ewes received a ration based on alfalfa (12.12% CP and 2.10 Mcal/kg ME) and pas- ture (6.85% CP and 2.13 Mcal/kg ME) hay, covering 50% of National Research Council nutritional require- ments for twin-bearing ewes to reflect commercial con- ditions. Maternal BW and BCS were recorded every 10 d, from 100 dg until lambing. Maternal blood samples were collected at 130 dg and 30 min after lambing and plasma beta-hydroxybutyrate (BHB), total protein, albumin and urea were evaluated. Colostrum was collected 30 min after the second lamb was delivered and fat, non-fat solids, density and protein contents were determined. The effect of treatment on ewe BW, BCS were analyzed using REML analysis in R (lme4 R package) with time (dg) and treatment (and their inter- action) as fixed effects. Plasma and colostrum metab- olites were analyzed using REML with treatment as the fixed effect. Ewe BW increased (P < 0.0001) and BCS decreased (P < 0.0001) with advancing gestation, but there was no effect of treatment (P > 0.05). At 130 dg plasma urea was a 12% greater (P = 0.02) and al- bumin tended to be 4% greater (P = 0.08) in NCG com- pared with CON ewes, but no treatment effect on BHB or total protein content was observed (P > 0.05). No treatment effect on maternal plasma metabolites were observed post lambing (P > 0.05). Colostrum protein content was 21% greater in NCG compared with CON (P = 0.04) ewes, but fat, non-fat solids or density (P > 0.05) did not differ between groups. Collectively, these results suggest that supplementation of nutritionally restricted ewes with 60 mg/kg BW from 100 dg to lambing may alter maternal nitrogen metabolism and colostrum protein content. The potential impact of these changes on lamb growth and/or survival, warrants further investigation. *Funded by FONDECYT Project N°1221042; AgResearch Strategic Science Investment Fund SSIF-A25765 and INIA Kampenaike. [ABSTRACT FROM AUTHOR]

• Maternal nutrient restriction reduces lamb birth weight and future performance. • Ram lambs born to supplemented ewes were heavier until first 4 months old. • Males born to restricted ewes showed greater sexual activity at 6 and 12 months-old. • Males from supplemented ewes tended to have a lower sperm count at 6 months of age. Southern Patagonia offers harsh environmental and nutritional conditions for sheep pregnancy, which may compromise the fetal and postnatal development of lambs. The aim of the study was to compare the sexual behavior and attractiveness, and semen production and quality during the first year of life of ram lambs born to undernourished mothers grazing on natural pastures, supplemented or not with a concentrate. The study was performed under extensive Patagonian conditions, and a supplement was provided from day 44 of gestation until lambing. Twelve ram lambs born to supplemented ewes (group Sup) and 12 born to control underfed ewes (group Con) were used. Both groups of male lambs remained in a common paddock before and after weaning at 4 months-old. Sexual behavior and attractiveness, and semen production and quality of ram lambs were evaluated when they were 6 and 12 months-old. Sup lambs were heavier than Con at birth, and tended to maintain this difference when they were 4 mo-old; afterward, this difference disappeared. At 6 months-old, Con ram lambs displayed greater sexual activity when individually exposed to an estrous ewe, as well as a trend to a greater sperm concentration. Differences between groups in sexual behavior decreased at 12 months-old, and no differences were detected in seminal traits. In conclusion, supplementation of undernourished pregnant ewes with concentrate from mid-pregnancy until lambing slightly impacted the progeny reproductive performance when they were 6 months-old, an effect that was attenuated at 12 months-old. The effects of the nutritional status of pregnant ewes on the reproductive development of the offspring likely were compensated by a greater growth rate during early life before puberty. [ABSTRACT FROM AUTHOR]

Nutrient restriction in sheep during pregnancy normally occurs in Patagonia with negative effects on ewe body condition (BCS) and reproductive performance. N-carbamylglutamate (NCG), an analogue of N-acetylglutamate, is postulated to improve urea recycling, nitrogen utilization and antioxidant capacity in ruminants. The objective of this study was to evaluate the effect of oral NCG supplementation in naturally nutrient restricted grazing twin-bearing ewes, on maternal body weight (BW) and body condition score (BCS), serum biochemical indexes and antioxidant capacity in mid-late gestation. Ten twin-bearing ewes were orally dosed once-daily with 60 mg/kg BW NCG in a water carrier from 100 to 140 days of gestation (dg) and were compared with unsupplemented controls (CON; n = 8). Maternal BW, and BCS were recorded every 10 days, from 100 to 140 dg. Blood samples were collected at the same time points to evaluate plasma metabolites (NEFA, urea, total protein, albumin, globulin, Ca, P, Mg, Cholesterol, ASAT, CK, GGT, GLDH, total bilirubin and triglycerides), antioxidant status [malondialdehyde (MDA)], and total antioxidant capacity (TAC). Ewes were managed as a single mob in a paddock with natural pasture (3.3% CP, 1.9 Mcal/kg ME), supplemented with alfalfa hay (600 g· ewe-1·/day-1; 13% CP and ME 2.2 Mcal/kg ME) from 130 dg, with a stocking rate of 0.9 ewes per hectare and a dry matter availability of 525 kg per hectare, representative of Patagonian prairie conditions. The effect of treatment on ewe BW, BCS and plasma metabolites were analyzed using REML analysis in R using lme4 R package with time (dg) and treatment (and their interaction) as fixed effects and animal as the random effect. Ewe BW increased (P < 0.0001) and BCS decreased (P = 0.005) with advancing gestation, but there was no effect of treatment. There was a tendency for a treatment effect (P = 0.07) on plasma urea with ~10% less concentrations in NCG than CON ewes at 130 dg (P = 0.08) and 140 dg (P = 0.04). There was a treatment by time interaction for total bilirubin (P = 0.005), phosphorus (P = 0.02), and a similar trend for albumin (P = 0.09). Ewes supplemented with NCG had~10% lower concentrations of bilirubin at 100 (P = 0.01) and 120 dg (P = 0.04), less concentrations of phosphorus (P = 0.003) and albumin (P = 0.02) at 140 dg compared with CON ewes. No other effects of treatment on blood metabolites or antioxidant status or capacity were observed. Collectively these results suggest that supplementation of nutritionally restricted ewes with 60 mg/kg BW from 100 to 140 dg did not influence BW or LWT but may have some effects on liver function, protein metabolism, urea recycling, feed intake and/or feed efficiency which warrant further investigation.*Funded by FONDECYT Project N°1221042; AgResearch Strategic Science Investment Fund. [ABSTRACT FROM AUTHOR]

Simple Summary: In twin-bearing ewes, undernourishment during pregnancy lowers the birth weight and increases morbidity and mortality of lambs. One of the causes is oxidative stress, which can be prevented by supplementing antioxidant vitamins. In the present study we tested the effect of supplementation with herbal vitamins C and E alone or in combination with concentrate on pregnancy outcomes and growth and survival of lambs during early postnatal stages (lactation). The results showed that vitamin supplementation increased offspring birth weight and antioxidant capacity, with a trend towards higher body weight (BW) at weaning. Nutritional supplementation only had a positive effect on birth weight, meanwhile combined supplementation of vitamins and concentrate improves the lamb response. Lambs' survival was not affected by the treatment, although absolute values of survival were higher in vitamin-treated groups. It is concluded that supplementation with herbal vitamins C and E alone or in combination with concentrate during pregnancy may constitute a good nutritional strategy to improve productivity in sheep herds reared in harsh environmental conditions. Twin-bearing pregnancies of sheep reared in harsh environmental conditions result in maternal undernutrition and feto-maternal oxidative stress, leading to intrauterine growth restriction (IUGR). We assessed the efficiency of supplementation with antioxidant herbal vitamins C and E alone or in combination with concentrate throughout gestation on pregnancy outcomes, pre-weaning growth, and survival of twin lambs from grazing ewes at the Magellan Steppe. Four groups (n = 30 each) of twin-bearing ewes received a base natural prairie (P) diet, supplemented with either herbal vitamins C 500 mg and E 350 IU per day (V) or concentrated food (S); groups were: P, P + V, P + S, and P + VS. Vitamins and concentrate were supplemented until parturition. At birth, lambs were weighed, and blood was drawn for total antioxidant capacity (TAC) evaluation. Lamb body weight (BW) and survival rate were evaluated at mid-lactation (60 days) and at weaning (120 days). Vitamin supplementation resulted in increased lamb birth weight and TAC, with a trend towards higher BW at weaning, while nutritional supplementation only had a positive effect on birth weight. Lamb survival was higher in both vitamin supplemented groups. In conclusion, supplementation with herbal vitamins C and E alone or in combination with concentrate food during pregnancy may constitute a good nutritional strategy for sheep reared in harsh environmental conditions. [ABSTRACT FROM AUTHOR]

• A protein-dense supplement enhanced use of the unpalatable shrub romerillo by ewes. • Polyethylene glycol did not influence intake of romerillo by ewes. • Protein supplementation enhanced dry matter retention in wethers consuming romerillo. Romerillo (Chiliotrichum diffusum) is an unpalatable and invasive shrub occurring in over 1 M ha of Magellan rangelands, which constraints livestock operations and reduces biodiversity. Low nutrient content and the presence hydrolizable tannins (HT) explain the low palatability of the shrub. We determined whether supplemental macronutrients (Exp. 1) or polyethylene glycol (PEG; Exp. 2), a compound that reduces bioavailability of tannins, enhance intake of romerillo by sheep. An in vivo digestion trial (Exp. 3) assessed the influence of nutrient supplementation on apparent DM digestibility in sheep fed romerillo. In Exp. 1, 28 yearling ewes were penned individually and randomly assigned to 4 groups (7 ewes/group), where they had supplements high in energy (HE; corn), high in protein (HP, canola meal), a choice between HE and HP (CH), or no supplement (Control; C). Subsequently, all ewes had ad libitum amounts of freshly cut romerillo followed by 1% BW of grass hay. Intake of romerillo was HP > C > HE (8.4, 6.3, 4.5 g/Kg BW, respectively; P < 0.05), and ewes in CH selected a 67:33 proportion of corn:canola meal that only tended to reduce romerillo intake relative to HP (6.8 g/Kg BW; P = 0.074). Ewes maintained (HP, HE), reduced (C) or increased (CH) their BW during 26 d of experimental feeding (P < 0.05). In Exp. 2, thirty-two yearling ewes were assigned to a 2 × 2 factorial design (8 ewes/group), with PEG (1-yes, 2-no) and Supplement (1-HP; 2-Mix:67:33 proportion corn:canola meal) as factors, and fed as in Exp. 1. PEG did not affect romerillo (3.4 % HT) intake (P > 0.05), but ewes supplemented with HP showed the greatest intakes of the shrub (6.6 g/Kg BW; P = 0.0002). In Exp. 3, 15 wethers were housed in metabolic crates and assigned to HP, C and Mix treatments (5 animals/group), and fed as in Exp. 1. Romerillo intake did not differ among groups, but the group HP tended (P = 0.0874) to show greater values of digestibility than the group C, and the supplemented groups presented greater DM retention values (P < 0.05). Thus, protein supplementation or choices between energy- or protein-dense supplements in targeted browsing programs have the potential to enhance use of romerillo by ewes in Magellan rangelands while maintaining or enhancing animal BW. In contrast, PEG supplementation did not affect shrub intake and energy-dense supplements reduced romerillo intake relative to unsupplemented animals. [ABSTRACT FROM AUTHOR]

• Romerillo intake increased with the level of protein supplementation. • Romerillo intake was constrained by increasing the ME/CP ratio in the supplement. • Appropriate supplementation optimizes targeted browsing programs. Romerillo (Chiliotrichum diffusum) is an unpalatable and invasive shrub that reduces biodiversity and constraints livestock operations in the Magellan rangelands of southern Chile. Nutrient and energy inputs may enhance romerillo use by sheep, reducing its competitive capacity and restore biodiversity loss. In Exp. 1, 32 ewes were penned individually and randomly assigned to 4 groups (8 ewes/group), where they were supplemented with 1 (Group 1), 3 (Group 2), 5 (Group 3), or 7 g/Kg BW/d (Group 4) of canola meal, a high-crude protein (CP) supplement. Subsequently, all ewes had ad libitum amounts of freshly cut romerillo followed by 1% BW of grass hay. Intake of romerillo increased with the amount of canola meal offered up to 5 g/Kg BW (P < 0.0001), but ewes supplemented at 7 g/Kg BW ate amounts of romerillo comparable to ewes supplemented at 3 or 5 g/Kg BW (P > 0.05), reflected in a negative quadratic relationship between romerillo and canola meal intake (P < 0.001). In Exp. 2, 24 ewes were randomly assigned to three treatment groups (8 ewes/group), where they received a constant amount (2.5 g /Kg BW/day) of supplements with declining ratios of CP to metabolizable energy (ME): Canola meal (Group 1), a commercial pellet (Group 2), and a mix of corn:canola meal with a proportion (67:33) ewes typically select when consuming romerillo (Group 3). Romerillo and hay were fed as described for Exp 1. Ewes supplemented with canola meal ingested more romerillo than ewes supplemented with the mix (P < 0.05), and tended to consume more shrub than ewes supplemented with the commercial pellet (P = 0.06579). The relationship between romerillo intake and supplemental level of CP showed a positive linear effect (P < 0.05), whereas the relationship between shrub intake and supplemental level of metabolizable energy (ME) showed a quadratic effect (P < 0.001) with a minimum at the greatest values of ME intake. Collectively, these results suggest a negative effect of incremental levels of supplemental ME on romerillo intake, provided that the concentration of CP in the supplement declines. Thus, the level of supplementation and CP:ME ratio in the supplements both influenced romerillo intake by ewes, where the ratio observed in canola meal and the level of 5 g/kg BW/d represented the best options - out of those assayed - for maximizing romerillo intake. These quantities and ratios give insights into how nutrients interact with defended and unpalatable plants in the community during the foraging process, contributing to the optimization of targeted browsing programs, aimed at improving the efficiency of the vegetation management plan, as well as the nutrition and welfare of the herbivore. [ABSTRACT FROM AUTHOR]