Supplemental fishmeal in vitro may boost lamb health

By Aerin Einstein-Curtis

- Last updated on GMT

Supplemental fishmeal in vitro may boost lamb health

Related tags Immune system

The inclusion of fishmeal in the diets of pregnant sheep may help protect offspring from maternal stress events, says a Canadian research team.

Maternal stress may have a negative effect on developing offspring, but use of n-3 polyunsaturated fatty acids (PUFA) supplement like fishmeal in the diet may help mitigate that, researchers said in the BMC Veterinary Research journal. 

“The purpose of this study was to investigate whether maternal fishmeal supplementation during pregnancy and lactation protects against programming of the offspring’s immune response following simulated maternal infection,”​ they said.

Why stress

Maternal stress is increasingly thought to influence offspring development and the immune system, said researchers. Stress events can lead to offspring that are more susceptible to inflammatory disorders.

“It is speculated that genetic predisposition itself cannot be solely responsible, and focus is being placed on in utero events and environmental factors that may be playing a contributing role,” ​they said. “Prenatal stress and the associated rise in glucocorticoids (GCs), as well as the high concentration of pro-inflammatory mediator omega-6 polyunsaturated fatty acid (n-6 PUFA) has been found to be a factor contributing to the susceptibility to atopic diseases by altering the programming of both the immune system and hypothalamic-pituitary-adrenal axis (HPAA).”

However, when the supplement is added to the diet also seems to influence how effective the additive is, they said. Some postnatal experiments have not shown positive results, which is why this study looks at supplementing the diet of pregnant ewes.


In the experiment 53 ewes were given one of two diets containing either supplemental fishmeal (FM) with n-3 PUFA, or soybean meal (SM) with n-6 PUFA, said researchers. The diets started on day 100 of gestation and continued through 50 days of lactation.

The soybean diet was considered the control diet, they said. And, sheep were fed twice a day.

“Ewes were housed individually indoors in an 8′ × 4′ pen and offered feed twice a day at 2.5 % of body weight for a total amount of 2.64 kg of feed/day (0.312 kg supplement, 0.441 kg mixed grain, 0.630 kg chopped hay and 1.261 kg alfalfa pellet) with average feed intake of 2.53 kg of feed/day in the FM group and 2.59 kg of feed/day in the SM group during gestation​,” they said. “During lactation 3.90 kg of feed/day was offered (0.455 kg supplement, 0.652 kg mixed grain, 0.931 kg chopped hay and 1.862 kg alfalfa pellets) with average feed intake of 3.83 kg of feed/day in the FM group and 3.877 kg of feed/day in the SM group.”

After 50 days lactation, all lambs were fed the same diet of a lamb grower and hay, they said. 

On day 135, half the ewes from each diet group were challenged with either a control saline injection or 1.2 µg/kg Escherichia coli​ lipopolysaccharide (LPS) endotoxin, researchers said. The offspring were tested for dermal immune response at 4.5 months.

To test for response, the group used a cutaneous hypersensitivity test with ovalbumin (OVA) and candida albicans​ (CAA) 21 days post sensitization, researchers said. Additionally, skinfolds were measured and blood samples were collected on day 1, 10 and 21 post sensitization and checked for “primary and secondary immunoglobulin G (IgG) antibody-mediated immune response.”


All the lambs survived the experiment and there were no significant differences in body weight among the different treatments, said researchers.

“Supplementation during pregnancy with FM appears to protect against adverse fetal programming that may occur during maternal infection and this may reduce the risk of atopic disease later in life,”​ researchers said.

All the lambs developed thicker skinsfolds from the hypersensitivity challenge, researchers said. And lambs from ewes that had the soymeal diet and LPS challenge had the largest increase in skinfold thickness compared to the other groups.

“There was also a three-way interaction of diet by treatment by quadratic time between the FM + LPS lambs and the SM + LPS lambs to the CAA antigen,”​ they said. “Therefore, quadratic time trends differed between dietary groups but also between treatment groups.”

Similarly, lambs from the ewes that had the soy diet and LPS challenge had an elevated OVA-specific IgG response for both the first and second immune response when compared to the other groups, researchers said.

“As expected offspring born to mothers supplemented with SM and challenged with endotoxin had the greatest secondary antibody response to OVA antigen as well as the greatest increase in skinfold thickness to both OVA and CAA compared to all other treatment groups,”​ they said.

Source: BMC Veterinary Research

Title: Fishmeal supplementation during ovine pregnancy and lactation protects against maternal stress-induced programming of the offspring immune system

DIO: 10.1186/s12917-015-0573-8

Authors: Rebecca Fisher-Heffernan, Mamun Or’Rashid, Ousama AlZahal, Margaret Quinton, Herman Boermans, Brian McBride, Timothy Regnault and Niel Karrow

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