
Ewe suplementation and spring rise / Valledor-Echegaray et al. ____________________________________________________________________
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INTRODUCTION
Sheep (Ovis aries) production faces different daily challenges, 
and parasitosis is one of the most important [1]. Among them, 
gastrointestinal nematodes (GIN) are the main ones, and, in Uruguay, 
the genus diagnosed are Haemonchus contortus (43%), Trichostrongylus 
axei (12%), Nematodirus spp. (11%) and Trichostrongylus spp. (26%) [2]. 
The incidence of the different GIN is determined by their pathogenic 
potential (PP), biotic potential (BP), and the number of parasites 
present, and all of them make the Pathogenicity Index (PI) vary [3].
GIN reduce voluntary intake by 10%, generating a body weight (BW) 
reduction of 33% in adult animals [4] and of 23.6% in the rearing [1]. 
Moreover, if infection occurs before the lambs are one month old, 
there is no effect on their body condition score (CS) [4, 5].
Adult sheep have immunity to GIN that allows them to perform 
productively [6], while lambs (3–6 months) do not eliminate their rst 
infection, generating parasitic disease where Trichostrongylus spp. 
produces acquired and specic immunity faster than H. contortus 
[1]. The response of sheep to a parasitic challenge depends on age 
and nutritional status level [7, 8, 9, 10, 11, 12, 13, 14], and frequency 
of challenges and genetic factors [15]. Despite this power of 
response, in breeding ewes, immune weakening occurs in the period 
immediately after lambing, known as “spring rise” [16, 17, 18, 19, 20]. This 
epidemiological phenomenon is measurable through the signicant 
increase in egg elimination per gram of faeces (EPG) of GIN. In addition, 
it allows massive contamination of the paddock and acts as a source 
for susceptible lambs before weaning [2, 18]. In Corriedale sheep, the 
spring rise has been determined between the sixth and eighth week 
postpartum in Uruguay [21] and United Kingdom [22]. In Australian 
Merino ewes, this phenomenon coincided with peak milk production 
(2–4 weeks postpartum) [23].
Increases in prolactin levels associated with parturition and lactation 
have been shown to have a suppressive effect on the immune system, 
reducing IgA levels, which favours increased fertility of H. contortus and, 
therefore, of EPG [24]. Immunorelaxation also occurs due to increased 
energy and protein requirements in postpartum and lactation [9]. In 
addition, at 2 to 3 weeks postpartum, the emergence of hypobiotic 
larvae (L4) of H. contortus from the mucosa is another critical factor in 
spring rise [1]. Pastures have higher parasite loads due to this increase 
in faecal egg counts (FEC), which is more marked when lambing takes 
place in spring [19, 25, 26].
The lamb is subjected to two sources of parasitic infectation, one 
being the dam herself and the other due to residual ingestion of 
infesting larvae (L3) from previous grazing [27, 28].
The emergence and development of anthelmintic resistance (AR) in 
sheep, mainly Trichostrongylus spp. and H. contortus was generated by 
the exclusive use of anthelmintics as the sole control measure [29, 30].
However, changes in nutritional management in sheep can inuence 
GIN behaviour [7, 8, 9, 10, 11 ,12, 30]. Donaldson et al. [25] indicated 
that the increase in EPG that occurs in peripartum in Coopworth 
ewes and the environmental contamination produced from this EPG 
can be reduced by protein supplementation to ewes from the month 
before lambing. Nutritional protein supplementation benets the 
immune response in sheep [1, 13, 14, 31], although Provenza et al. [32] 
indicated that protein supplementation without an energy source 
could generate adverse effects due to excess ammonia.
Therefore, this research aimed to determine the influence of 
protein–energy supplementation on the GIN population at spring 
rise in ewes and their offspring as a non–chemical alternative in 
Integrated Parasite Control (IPC).
MATERIALS AND METHODS
The trial was conducted at the Experimental Station Nº 1 of the 
Facultad de Veterinaria (Canelones, Uruguay, 34°37'28" Latitude; 
55°60'27" Longitude) from May to December 2015.
Animals
A total of 126 full–mouths Corriedale ewes, individually identied, 
were used. The ewes were selected from a flock of 300 animals, 
blocked by age, CS, body weight (BW), tooth and hoof condition, thus 
homogenising the sample. The ewes were synchronised in March with 
intravaginal sponges containing 160 mg of progesterone (Cronipres® 
CO, Biogénesis–Bagó) previous articial insemination [33]. Transrectal 
ultrasonography was carried out in May when 126 ewes with single 
gestation were selected. Lambing lasted from August 22
nd
 to August 31
st
.
During the whole trial, the animals were grazing on natural pasture, 
mainly composed by Cynodon dactylon. In February, the ewes were 
dosed with Naftalophos 80% (Baymetin, Laboratorio BayerR, Uruguay).
The ewes were supplemented with protein–energy  blocks 
(Metabolisable Energy = 8.8 MJ·kg
-1
, protein = 15%; Compañía Cibeles 
SA.) at a rate of 300 g·day
-1
 from August 12
th
 to December 9
th
 (weaning of 
the lambs). An adaptation period of 10 days (d) to feeding with the blocks 
was carried out in a small paddock. During this period, one person 
was responsible for identifying those ewes that ate the supplement, 
making four daily observations of 1 hour. At the end of this period, the 
animals were divided into two groups: the supplemented group (GS, n= 
54) and the non–supplemented group (GC, n= 72), and were located in a 
new paddock, which was divided into equal parts by an electric fence.
Determinations in sheep
From August 12
th
 to November 22
nd
, faecal samples were collected 
every 17 d from 20 animals (randomly) from both experimental groups. 
These were directly obtained from the rectum [34], conditioned and 
identied in nylon bags (without air) and transported refrigerated to 
the laboratory [34, 35].
Determinations in lambs
From October 7
th
 to December 9
th
, faecal samples were taken every 17 
d from 20 lambs (randomly) born to dams of both experimental groups 
and were obtained and conditioned in the same way as in the dams.
BW was determined in all lambs at birth, at marking (average age: 
22 d) and at weaning (average age: 98 d) using a digital scale (Baxtran, 
UCS30, Spain). Average daily gain (ADG) for the birth–marking and 
marking–weaning periods were calculated.
Laboratory analysis
Faecal samples from ewes and lambs were processed at the 
Facultad de Veterinaria Parasitology Laboratory. Modied McMaster 
technique was carried out using a McMaster camera (INTA, Argentina) 
and a microscopy with 40× sensitivity (Olympus, model CX21, Tokyo, 
Japan) [36]. The technique was based on FEC, and the result was 
expressed in eggs per gram of faeces (EPG). Coproculture (CL) was