Volume 191, Issues 1–2, 16 January 2013, Pages 51–58
Effect of supplemental sericea lespedeza leaf meal pellets on gastrointestinal nematode infection in grazing goats
Abstract
Feeding sun-dried sericea lespedeza [SL; Lespedeza cuneata
(Dum-Cours.) G. Don.] reduces gastrointestinal nematode (GIN) infection
in goats fed in confinement, but effects of this forage when fed as a
supplement to goats on pasture are unclear. A study was completed in
which supplemental feeds (75 and 95% SL leaf meal pellets and a
commercial pellet, all fed at 0.91 kg/head/day) were offered to thirty
growing male Spanish goats (9 months old, 20.6 ± 2.8 kg, 10/treatment)
grazing perennial warm-season grass pastures in Fort Valley, GA, from
September to November, 2010. Fecal and blood samples were taken from
individual animals weekly to determine fecal egg count (FEC) and packed
cell volume (PCV), respectively, and animal weights were recorded at the
start and end of the trial. After 11 weeks grazing, animals were
slaughtered for recovery, counting, and speciation of adult GIN from the
abomasum and small intestines. There was no difference in FEC between
goats fed the 75 and 95% SL leaf meal pellets, but both groups had lower
(P < 0.05) FEC than the goats fed the commercial pellets
from days 35 to 77. The PCV values were not affected by the dietary
treatments. Animal gain per day averaged 102.0, 77.2, and 53.3 g for
goats fed 95% SL, commercial, and 75% SL pellets, respectively (P < 0.05). The 95% SL leaf meal pellet goats had 93.0 and 47.3% fewer (P < 0.05) total (male + female) adult Haemonchus contortus and Teladorsagia circumcincta, respectively, than control animals, while only male H. contortus were lower (47.6%; P < 0.05)
in 75% SL-fed goats compared with commercial pellet-fed animals.
Feeding supplemental SL leaf meal pellets improved animal performance
(95% SL pellets) and reduced worm burdens (75 and 95% SL pellets) in
young grazing goats and is a useful tool for natural GIN control in
small ruminants.
Keywords
- Goats;
- Haemonchus contortus;
- Gastrointestinal nematodes;
- Sericea lespedeza
1. Introduction
Gastrointestinal
nematodes (GINs) are a major factor causing decreased productivity of
livestock worldwide, especially in grazing animals (Parkins and Holmes, 1989).
Poor growth rates, reduced reproductive performances, increased
mortality, and low quality products from infected animals eventually
increase production costs, and the problem is worse in tropical and
subtropical regions because of high prevalence of infected pastures due
to favorable environmental conditions for parasites to survive in their
free-living stage (Waller, 1997a and Waller, 1997b).
Poor quality forages, especially during the warm season, and extensive
grazing on unimproved pastures, together with lack of supplemental
nutrients, increases susceptibility to infection (Wan et al., 1989).
Anthelmintic drug treatment has historically been the most common
control method against GIN infection. However, there has been overuse
and misuse of this approach in the last 4–5 decades, which has led to a
world-wide increase in prevalence of anthelmintic resistance among major
nematode species in small ruminants (Bjorn et al., 1990, Ngomuo et al., 1990, Prichard, 1994 and Lans and Brown, 1998). In a report from Georgia, over 90% of goat farms had high levels of GIN resistance to ivermectin and albendazole (Terrill et al., 2001). In a more recent report, Howell et al. (2008)
reported total anthelmintic failure (resistance to all available
anthelmintics) on 17% of sheep and goat farms throughout the
southeastern USA. Therefore, alternative, sustainable methods of control
that are less reliant on chemotherapeutics are urgently needed.
There
have been a number of reports documenting reduced GIN infection levels
in sheep and goats grazing condensed tannin (CT)-containing forages,
including sulla (Hedysarum coronarium L.), birdsfoot trefoil (Lotus corniculatus L.), big trefoil (Lotus uliginosis Schkuhr.), and sericea lespedeza [SL; Lespedeza cuneata (Dum-Cours.) G. Don.] ( Niezen et al., 1995, Niezen et al., 2002, Min and Hart, 2003, Min et al., 2004, Shaik et al., 2006 and Terrill et al., 2009). Apart from parasite control, CT can also help to increase protein utilization efficiency by the animal ( Mueller-Harvey, 2006 and Scharenberg et al., 2007)
and decrease the incidence of bloat by altering ruminal gas production
and soluble protein digestibility from highly digestible forages ( Min et al., 2005).
There
are some limitations to the use of fresh CT forages, including seasonal
growth patterns, land requirement for grazing CT forages, and
unfavorable economics with some plant species. To help overcome these
problems, dried forms of CT forages can be used. There are a number of
reports showing good anti-parasitic efficacy of sun-dried SL (Shaik et al., 2004, Shaik et al., 2006, Dykes et al., 2006, Lange et al., 2006 and Terrill et al., 2008), sainfoin (Onobrychis viciifolia Scop.; Paolini et al., 2003), and acacia (Acacia karoo; Kahiya et al., 2003).
Pelleted SL hay maintained its anthelmintic effectiveness against GIN
of goats and could potentially increase the utility of this forage as a
natural deworming agent for small ruminants ( Terrill et al., 2007).
All of these reports involved feeding dried forages to parasitized
animals in confinement trials. There have been no published reports on
the effect of supplementation with CT forage pellets on GIN infection in
grazing goats.
Bermudagrass [Cynodon dactylon
(L.) Pers.] is well-adapted to the southeastern USA, except on poorly
drained soils, and is the primary pasture grass in this region. Forage
quality of perennial warm-season grasses, including bermudagrass, is
generally lower than that of cool-season grasses, and at the same time,
transformation of Haemonchus contortus eggs into infective (L3) larvae is much higher during warmer months when warm-season grasses are growing ( Eysker et al., 2005).
Supplementing perennial warm-season grass pasture with SL pellets may
help to control GIN and improve performance of meat goats under
perennial grass-based grazing systems.
The
objective of this research to test the effectiveness of supplementing
with SL pellets to control GIN and improve performance of goats grazing
perennial warm-season grass pasture during late summer/autumn.
2. Materials and methods
2.1. Experimental animals and design
An
experiment was conducted at the Fort Valley State University (FVSU)
Agricultural Research Station, Fort Valley, GA, and all husbandry
practices and experimental procedures used in the study were approved by
the FVSU Animal Care and Use Committee. All animals were naturally
infected by grazing contaminated pastures before the experiment was
started. Animals with blood packed cell volume (PCV) ≤ 15 at any time
throughout the study period were dewormed with a combination of
levamisole and doramectin.
The
experiment was completed during the late summer–autumn grazing season
on mature perennial warm-season grass pastures ((primarily bermudagrass
and bahiagrass (Paspalum Notatum Flugge.)). Treatment paddocks
(0.32 ha) each contained an automatic feeder (Tarter Farm and Ranch
Equipment, Dunnville, KY) in which supplemental feed pellets were
offered to grazing goats. Thirty naturally-infected intact male Spanish
kids (9 months old, 20.6 ± 2.8 kg) were stratified by FEC and randomly
assigned to 3 groups (n = 10/group), with each group then
randomly assigned to the 3 pastures. The goats were offered
0.91 kg/head/day of 1 of 3 pelleted rations: (1) 95% SL leaf meal, (2)
75% SL leaf meal, or (3) commercial (control) pellets ( Table 1).
The goats began consuming all three diets immediately after they were
offered, and there were no pellets left in the automatic feeders at the
end of each feeding period (24 h).
- Table 1. Chemical composition of supplemental 95% sericea lespedeza (SL) leaf meal, 75% SL leaf meal, or commercial pellets offered to grazing goats (all values expressed on dry matter basis).
Pellet Constituent
ECTa PBCT FBCT TCT CP % NDF % ADF % Commercial 0.0 0.0 0.0 0.0 19.6 15.0 9.4 75% SL leaf meal 3.51 2.13 0.02 5.66 18.5 23.1 17.1 95% SL leaf meal 3.10 2.57 0.04 5.71 15.1 26.2 20.3 -
- a
- ECT = extractable condensed tannin; PBCT = protein-bound condensed tannin; FBCT = fiber-bound condensed tannin; TCT = total condensed tannin; CP = crude protein; NDF = neutral detergent fiber; ADF = acid detergent fiber.
The
75 and 95% SL pellets were made from two different cuttings of SL hay
grown in Central Alabama (Sims Brothers Seed Company, Union Springs,
AL). The 95% SL pellets were made at the FVSU Agricultural Research
Station using a small pellet mill (California Pellet Mills, Ames, IA)
and consisted of 95% SL leaf meal, 4% dried molasses, 0.5% vitamin
premix, and 0.5% trace mineral salt. The 75% SL pellets (75% SL leaf
meal, 13.25% cracked corn, 6.75% cottonseed meal, 5% liquid molasses)
were made at a USDA Research Station in El Reno, OK. Control pellets
were purchased at a local feed mill (Mid-Georgia Farm Services, Inc.,
Montezuma, GA). The spring and early summer growth on the pastures was
removed prior to the start the trial, and grazing was initiated on
summer regrowth. The goats were set-stocked for 11 (September–November)
weeks grazing.
Blood and
fecal samples were taken weekly from individual animals for FEC and PCV
determination, respectively, and the goats were then transferred to the
FVSU Meat Technology Center and humanely slaughtered for recovery of
adult GIN from the abomasum and small intestines for counting and
speciation. The PCV data for the initial 2 sampling periods had to be
discarded due to use of expired hematocrit tubes. Animal weights were
recorded at the start and end of the trial, with pre-slaughter shrink
weights and carcass weights recorded for the goats
