Invited review: impact of specific nutrient interventions during mid-to-late gestation on physiological traits important for survival of multiple-born lambs

Abstract

To improve production efficiency, the sheep meat industry has increased flock prolificacy. However, multiple-born lambs have lower birth weights, increased mortality and reduced growth rate compared with single-born lambs. Lamb mortality is a major issue for livestock farming globally and solutions are required to increase survival to realise the value of increased flock fecundity. Nutrition during gestation can influence maternal-foetal placental nutrient transfer and thus foetal growth and organ/tissue development, as well as improve postnatal productivity. This review covers the challenges and opportunities associated with increased prolificacy, highlights gaps in our knowledge and identifies some opportunities for how targeted intervention with specific nutrients during mid-to-late pregnancy may influence lamb survival and productivity with a specific focus on pasture-based systems. This time frame was selected as intervention strategies in short-time windows post-pregnancy scanning and before lambing to improve lamb survival in high-risk groups (e.g. triplets) are likely to be the most practical and economically feasible options for pasture-based extensive farming systems.

Hypoxia and Oxidative Stress Are Associated with Reduced Fetal Growth in Twin and Undernourished Sheep Pregnancies

“…The effects of twinning on fetal growth have also been studied in sheep. Independently of other concurrent factors, twinning is widely recognized as a detrimental factor for birth weight, with twins showing 13–20% lower weight than singletons [ 9 , 10 , 32 , 33 ], although such differences not always reach statistical significance [ 34 ]. In agreement with these reports, placental and fetal development were affected in twin pregnancies in the current study, which was associated with a decrease in fetal body weight of around 16% in twins when compared to singletons and an 8% reduced GI, which has been previously shown to be affected in fetuses under restricted conditions [ 25 ].…”

“…However, the antioxidant/oxidative status of the feto-placental units was affected only by twinning. Placental development is known to be affected by maternal undernutrition [ 37 ]; nevertheless, twinning has larger effects due to the limitation of uterine space necessary for adequate placental development [ 33 , 38 ]. Abnormal placental development is known to be related to placental insufficiency [ 39 , 40 ], which leads to inadequate transfer of nutrients and oxygen to the fetus and, therefore, to restricted fetal development.…”

“…In addition, twinning was associated with a state of oxidative stress of the feto-placental unit, which might also contribute to FGR. These results highlight hypoxia and oxidative stress in FGR fetuses resulting from maternal undernutrition and/or twinning as potential targets to reduce or ameliorate FGR in these situations, using new nutritional (e.g., rumen-protected amino acids or fatty acids; [ 33 , 57 , 58 ]) or antioxidant (e.g., vitamins C and E; [ 22 , 45 ]) intervention strategies in sheep flocks. Future research is needed to define appropriate strategic supplementation options that are suitable for extensive ovine systems such as the Chilean Patagonia system.…”

Efecto de la alimentación en la fase de lactancia sobre la eficiencia de utilización del alimento en el período posdestete y su relación con la microbiota del tracto digestivo, el estatus oxidativo e inmunológico en el ganado ovino = Effects of early feed restriction during the post-weaning period on feed efficiency, gastrointestinal microbiota, anti-oxidant status and immunity parameters of lambs

“…La disminución en el peso al nacimiento no es siempre un hallazgo constante, puesto que puede no verse afectado si el déficit de nutrientes tiene lugar en una fase temprana de la gestación (Ford et al, 2007). En todo caso, los corderos nacidos con bajo peso pueden presentar un peor ritmo de crecimiento y una mayor mortalidad durante las primeras etapas de vida en comparación con los corderos con mayor peso de nacimiento (Greenwood et al, 1998, McCoard et al, 2017, perjudicando gravemente el rendimiento económico de las explotaciones ganaderas. Asimismo, se han descrito alteraciones similares al síndrome metabólico humano en la descendencia de ovejas que recibieron una alimentación insuficiente durante la gestación, como el desarrollo de resistencia a la insulina e intolerancia a la glucosa , hipertensión arterial (Hawkins et al, 2000), engrasamiento visceral (De Blasio et al, 2007) o dislipidemia (Khanal et al, 2014).…”

“…La comunidad bacteriana epimural del rumen de los corderos alcanza en poco tiempo concentraciones similares a las de los adultos, mientras que su diversidad experimenta cambios significativos durante las primeras semanas de vida (Mueller et al, 1984, Rieu et al, 1989. A la microbiota epimural del rumen se le atribuyen importantes funciones como la utilización del oxígeno (Cheng et al, 1979), la hidrólisis de la urea (Wallace et al, 1979) y el reciclaje de tejido epitelial (McCoard et al, 2017), pudiendo también estar involucrada en el metabolismo de aminoácidos ) y de los ácidos grasos volátiles (Chen et al, 2012). Además, esta comunidad bacteriana puede colaborar con el sistema inmunitario porque compite contra los microorganismos patógenos que intentan adherirse al epitelio (Wetzels et al, 2015).…”