Thermogenesis, blood metabolites and hormones, and growth of lambs born to ewes supplemented with algae-derived docosahexaenoic acid1

Abstract

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.

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

“…Specific PUFA such as linoleic acid are a key energy source for BAT in lambs (Lammoglia et al, 1999). However, twinbearing Taghee ewes supplemented with 12 g/ewe per day of algae-derived DHA during the last 30 days of gestation had no effect on lamb thermogenesis (Keithly et al, 2011). In contrast, twin-bearing ewes fed rumen-protected fat which was high in saturated and monounsaturated fatty acids or high in n-6-and n-3-PUFAs at a level of 2% or 4% for the last 40 days of gestation may improve cold tolerance in newborn lambs (Chen et al, 2007).…”

“…Maternal supplementation with polyunsaturated fatty acid (PUFA) increases gestation length in several species (reviewed by Capper et al, 2006) resulting in a more physiologically mature foetus at birth. However, supplementation with 12 g/ewe per day algae-derived PUFA DHA in twin-bearing Targhee ewes in the last 30 days of gestation and early lactation had no effect on lamb birth weight (Keithly et al, 2011). Other studies have also demonstrated variable effects of trace elements and vitamins throughout gestation on lamb birth weight (reviewed by Rooke et al, 2008).…”

Opportunities and Implications of Pasture‐Based Lamb Fattening to Enhance the Long‐Chain Fatty Acid Composition in Meat

“…Consequently, a 135 g serve of algal‐supplemented lamb would provide 129 mg of long‐chain n‐ 3 fatty acids including EPA, DHA, and DPA (Ponnampalam ). Other studies have shown that high levels of long‐chain n‐ 3 fatty acids from algal supplementation could benefit other aspects of production, for example, fewer lamb mortalities due to increased transfer of immunoglobulins from colostrum thus increasing immunity (Keithly and others ). It has also been suggested that long‐chain n‐ 3 fatty acids may improve reproductive performance, as EPA and arachidonic acid (AA) are precursors of eicosanoids such as prostaglandin (Gulliver and others ).…”

“…The high nutritional value of legumes also impacts on other aspects of production including ewe lactation and lamb survival. Ewes were found to produce 25% more milk when grazing on legumes compared to grass, which consequently improved lamb weaning weights (Kenyon and others ; Hutton and others ) and is associated with improved triplet survival (Keithly and others ). Interestingly, lamb survivability is related to PUFA content as thermogenesis, which uses brown adipose tissue (BAT) as an energy source, is mainly fueled by linoleic acid.…”

“…This is thought to improve lamb survivability, because the transfer of linoleic acid from the ewe to its lamb via the placenta or milk could be used as an energy source within BATs. This could enable lambs to withstand harsher environmental conditions during the early stages of life due to the use of BATs during thermogenesis (Keithly and others ).…”