Forsøksdyr: Seaweed inclusion in ruminant diets: performance of growing-finishing lambs, and milk yield and quality from goats

Godkjenningsdato 05.07.2018

Objective: To assess the potential benefits of including seaweed in: (A) sheep diets on body weight change, changes in rumen microbiota and carcass quality, and (B) lactating goat diets on milk yield and quality. The experiment will involve 3 treatments (0% , 2.5 and 5% seaweed) for the lamb diets. For the goat experiment, 0% and 5% seaweed inclusion will be implemented. The lamb trial is planned for 35 days and goats for 14 days. Except for the low levels of seaweed, the rest of the diets will be standard growing lamb and lactating goat diets as used in the farm. The number of lambs required for this planned trial is 24 (i.e., 8 per dietary treatment), whereas we will re-use 6 rumen cannulated goats (previous FOTS ID 14866) (3 per dietary treatment). For both experiments, we plan to take rumen fluid samples. Stomach tubes will be used for lambs, and the goats are already rumen cannulated. Furthermore, blood samples will be taken for plasma analysis of metabolites. Experienced personnel will perform the sampling, and the animals will only be fixed for a very short time when samples are taken. Experience from previous trials indicates that this will only be a short period of discomfort for the animals while they are handled/fixed and sampled.

Expected adverse effects: These planned seaweed supplementation levels were chosen considering the energy density, digestibility and mineral concentration of the material, and similar levels have been used before with ewes in Norway without any adverse effects on ewe health and performance. Seaweed quality varies tremendously depending on location, year, season and depth of harvest, and this may influence the level of some minerals. The max level of 5% seaweed planned here is unlikely to create any negative health effects, but we will perform chemical analysis on the feeds before starting the experiment to make sure that the planned level is implemented.

Expected scientific or social usefulness of the experiment: The outcome will provide useful information regarding the use of locally produced feed resources like seaweeds in ruminant diets for meat, milk production and their qualities.

The planned experiments are complementary to large in vitro (bench) work where we assess the effects of rumen adaptation to seaweed on the extent and pattern of diet digestibility and methane production potential. The in vitro work will include seaweed levels used here plus additional graded levels of seaweed. We will thus evaluate many seaweed inclusion levels in vitro, but only 2 low levels in vivo. Furthermore, we are matching the lambs for breed, gender, age and weight at start of the experiment, which reduced the number of lambs in each group. The goats come from an ongoing trial, and here they will be reused, replacing milking cows and avoiding additional new cannulations. Furthermore, for the lamb experiment, we plan to collect rumen fluid samples without an invasive rumen cannulation in search of refining and replacing plausible techniques without compromising the planned objective.