Improving Feed Efficiency in Sheep Through Rumen Manipulation and Producer Adoption

Improving Feed Efficiency in Sheep Through Rumen Manipulation and Producer Adoption

Summary

All animal procedures were approved by the University of Wyoming (UW) Animal Care and Use Committee.

As part of a funded study that began on January 7, 2014, mature ewes (n = 80) fed a forage-based pelleted diet were assessed for individual feed intake over a 60 day period using the GrowSafe System at UW and feed efficiency was calculated from this data. For this study, residual feed intake, or RFI, was used as the measure of feed efficiency that is estimated as the deviation of true feed intake from expected feed intake; low RFI animals are considered more feed efficient, and high RFI animals less efficient. Rumen fluid samples (~50 mL per ewe) were collected via oral lavage on February 11, 2014 from all ewes and stored at -80° C until they were processed for DNA sequencing.

Five sets of Hampshire twin lambs (n = 10) from the University of Wyoming served as the recipients and set to receive rumen fluid inoculations from either a high RFI or a low RFI donor ewe from the study described above. Upon birth of each set of twin lambs, which were between March 29 and April 4, 2015, rumen fluid samples (~50 mL per donor) were collected from one low RFI donor ewe and one high RFI donor ewe via oral lavage; one twin lamb was inoculated (via oral gavage) with the low RFI filtrate, and the other with the high RFI filtrate within 8 hours of birth. A second inoculation (with fresh rumen fluid filtrate collected from the same donor ewes) was performed two weeks later once the rumen had started to effectively function; this served as “booster” to help encourage establishment of appropriate microbial populations. All lambs were raised by their dams in a similar environment in one pen. Lambs were weaned August 3, 2015 and received the same forage-based pelleted diet as their donors. Individual feed intake was measured using the GrowSafe System for a 70 day trial period that started August 10, 2015. Residual feed intake was estimated and rumen fluid samples were collected at day 35 from the twin lambs and stored as previously described. DNA was extracted from the rumen fluid collected from both donor and twin lambs (n = 4 donors; n = 10 lambs) and sent to the University of Missouri (MU) DNA Core Facility for sequencing. Final analysis is currently being completed to further define in inoculation type between twins and compared with adult donor sequence data.

Objectives/Performance Targets

The objectives of this research are to:

1) determine if inoculation of lambs at birth with rumen microbiota from adult sheep identified as highly efficient and lowly feed efficient alters the rumen microbial profile,

2) determine if lambs inoculated with highly efficient and lowly efficient adult microbiota demonstrate increased and decreased feed efficiency, respectively,

3) enhance producer adoption and application of feed efficiency measures in sheep through development of educational materials and generation of a feed efficiency selection index, and

4) determine the long-term economic implications of improving feed efficiency via rumen microbiota inoculation at birth.

Accomplishments/Milestones

In March and April 2015, five sets of twin lambs were inoculated successfully within 8 hours of birth, and a second inoculation was performed 2 weeks after they were born. A 70 day feed efficiency test was completed in October 2015 and DNA sequencing from rumen fluid samples was performed on five sets of twin lambs. Final analysis of sequence data is currently underway to compare microbial composition between twins and donors and among twin lambs. Producer educational materials are being developed based on the trial outcomes.  Educational materials include mailings of informational pamphlets to area producers (e.g., University of Wyoming Ram Test producers) regarding the importance of feed efficiency and ways to include this trait in selection decisions.  An update to the current selection index used at the University of Wyoming Ram Test has also been implemented (Spring 2016); producers have an interest in having feed efficiency as a part of that index. Finally, preliminary data has been collected for the planned economic analysis, which will be performed upon completion of the final analysis of the sequence data. We also plan to perform a functional analysis of the sequence data to better understand pathways underlying feed efficiency and determine potential responses to the inoculations. 

Impacts and Contributions/Outcomes

The impacts and outcomes are currently being determined. The results from the lamb trial are promising, as 3 of the 5 twin sets of lambs responded accordingly with their corresponding inoculant for feed efficiency. This would suggest that more research be conducted in this area of research, with a greater number of lambs. Additional research might also include determining the optimal time for inoculation, as well as determining if and when a booster inoculant is required.

Collaborators: