AUTHOR=Mwangi Paul M. , Eckard Richard , Gluecks Ilona , Merbold Lutz , Mulat Daniel G. , Gakige Jesse , Pinares-Patino Cesar S. , Marquardt Svenja 

TITLE=Impact of Haemonchus contortus infection on feed intake, digestion, liveweight gain, and enteric methane emission from Red Maasai and Dorper sheep

JOURNAL=Frontiers in Animal Science

VOLUME=Volume 4 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/animal-science/articles/10.3389/fanim.2023.1212194

DOI=10.3389/fanim.2023.1212194

ISSN=2673-6225

ABSTRACT=A study was conducted with Red Maasai and Dorper lambs to evaluate the effects of infection with the gastrointestinal nematode (GIN) Haemonchus contortus on feed intake, liveweight gain (LWG), feed energy and nitrogen partitioning, and enteric methane (CH4) emissions. Six-to seven-month-old Red Maasai (n=12) and Dorper (n=12) lambs were randomly allocated to three treatments (n=8, four lambs per breed) in a 2×3 factorial crossover study over two periods (P1 and P2) of 36 days each. Treatments consisted of combinations of GIN infection and feeding level: Infected + ad libitum feeding (I-adlib), uninfected + ad libitum feeding (Un-adlib), and uninfected + restricted feeding (Un-restd). Lambs in the I-adlib group were trickle-infected daily with 1,000 L3 larvae of H. contortus for four consecutive days, whereas lambs in the other experimental treatments were kept GIN free. Feed intake was measured daily. Liveweight (LW), faecal egg counts (FEC), and packed cell volume (PCV) were measured on Day 1 and weekly thereafter. On Days 29-33 total faecal and urine outputs were determined. Methane emission was then measured in respiration chambers for three consecutive days. There was a washout period of 21 days before P2 started. Uninfected lambs had undetectable FEC throughout the study. On Day 36, FEC did not differ between the breeds (P>0.05) while I-adlib had lower PCV than Un-adlib and Un-restd groups. Neither breed nor infection influenced feed and nutrient intake, but restricted-fed lambs had a lower intake (P<0.05).The LWG of Un-adlib lambs was significantly higher than that of I-adlib and Un-restd lambs (P<0.05) with no breed difference (P>0.05). Neither breed nor infection affected feed digestibility, nitrogen retention or energy metabolisability (P>0.05). However, feed restriction decreased feed intake, LWG and N retention, whereas feed digestibility and energy metabolisability were unaffected. Neither daily CH4 emissions nor yield were affected by infection, but Un-restd lambs had lower CH4 emissions per day. Red Maasai lambs had lower daily CH4 emissions and yields than Dorper (P<0.01). This study confirmed the relative resistance of Red Maasai sheep to H. contortus infection, but the increased CH4 emission and yield due to GIN observed in other studies was not confirmed.