AABArchives Animal BreedingAABArch. Anim. Breed.2363-9822Copernicus PublicationsGöttingen, Germany10.5194/aab-61-221-2018Body condition status at mating affects gestation length, offspring yield
and return rate in ewesBody condition status at matingCamMehmet Akifmakifcam@omu.edu.trhttps://orcid.org/0000-0003-3407-3913GaripogluAli VaizKirikciKorayhttps://orcid.org/0000-0001-8087-141XDepartment of Animal Science, Agricultural Faculty, Ondokuz Mayis
University, 55200 Atakum, Samsun, TurkeyDepartment of Animal Science, Agricultural Faculty, Ahi Evran
University, 40100 Kirsehir, TurkeyThese authors contributed equally to this work.Mehmet Akif Cam (makifcam@omu.edu.tr)13June201861222122823February201830April201825May2018This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/This article is available from https://aab.copernicus.org/articles/61/221/2018/aab-61-221-2018.htmlThe full text article is available as a PDF file from https://aab.copernicus.org/articles/61/221/2018/aab-61-221-2018.pdf
The present study was planned to determine the effect of ewe
body condition score (BCS) and parities on fertility, return rate, gestation
length, fecundity, litter size and lamb birth weight. Data were collected
from 284 heads of ewes with first to fifth parity and raised at a state farm
for three consecutive (2002–2004) years. Teaser rams were used to monitor
estrus twice daily in the morning and in the evening from September to
October. BCSs and body weights (BWs) were recorded at mating and postpartum.
The ewes, at mating time in breeding season and within first 6 h after the
expulsion of fetal membranes, were divided into four groups on the basis of
their BCS: thin (BCS =≤ 2.0; n=70; 38), medium
(BCS = 2.5–3.0; n=122; 142), fat (BCS = 3.5–4.0; n=72; 59) and
very fat (BCS =≥ 4.5; n= 20;17). BCSs and BWs of ewes at
postpartum were highly correlated with lamb birth weight (R=0.486,
P< 0.01, and R=0.130, P< 0.05, respectively). BCSs and BWs of
ewes at postpartum had positive effects on lamb birth weight
(Y=3.43± 0.10 + 0.130 + 0.047 ewe body condition score
(EBCS), P< 0.01;
Y= 2.92 ± 0.42 + 0.018 ± 0.009 ewe body weight
(EBW), P< 0.05 kg of lamb birth weight
per BCS and kilogram of ewe live weight, respectively). The fertility rate,
litter size and fecundity were higher in the medium and fat groups than thin
and very fat groups (χ2= 10.607, P< 0.01). The BW and BCS at
postpartum affected gestation length positively (P< 0.05). Return rate
or number of coitus for conception were higher (P< 0.05) in thin and
very fat groups than medium and fat groups. The data revealed that the ewes
with medium and fat body condition (BCS = 2.5–4.0) scores were
profitable.
Introduction
Body condition is both a good indicator, which reflects animals' feeding
status and general (or nutritional) well-being. Animal productivity has been
affected by body fat reserves or body condition score (BCS) (Roche et al.,
2009; Vatankhah et al., 2012; Kenyon et al., 2013) either positively or
negatively. Additionally, BCS is an important tool for good flock management
(Hocking et al., 2011; Van Burgel et al., 2011). Nutrition levels of animals
in a herd can be managed via monitoring their BCS (Keinprecht et al., 2016).
Farm owners' aims are to gain the most profit from each animal and to have a
homogeneous herd. However, these aims cannot be achieved easily due to the
competition between animals and genotypic differences in the herd.
Karayaka, a sheep breed reared locally in the Black Sea region, makes up
3 % of total sheep population in Turkey, and it is known to have
good-quality meat and low fecundity (Cam et al., 2010). However, the
fecundity can be increased via management procedures and breeding strategies.
Offspring yield has low heritability, and it was affected by environmental
factors (Cam et al., 2017). Accordingly, the body weight and body fat reserve
of a ewe can further influence lamb-producing ability and ewes' productivity
(Vatankhah and Salehi, 2010; Vatankhah et al., 2012). A sheep farmer who aims
to make a greater profit should have more lambs per parity. Good management
and well-balanced nutrition of the animals in a farm results in a good body
fat reserve and thus early development and early production.
The reproduction-related traits (return rate, fertility, litter size, dam
parity, dam BCS and dam live weight at mating, etc.) are affected by many
genetic and environmental factors. Therefore, reproduction results could not
be explained by merely one factor, and so the combined influence of factors
should be taken into consideration (Corner-Thomas et al., 2012; Corner et
al., 2013).
An animal's skeletal structure and fattening state are the main factors which
determine its body weight. Therefore, body weight alone is unable to define
an animal's body fat reserve state (Vatankhah et al., 2012). There are some
young animals with lower body weights (BWs) and higher BCSs as well as some
older animals with higher BWs and lower BCSs. On the other hand, the BW and
BCS of an animal are affected by parity. The parity affects an animal's
reproductive traits such as offspring yield, fertility rate and kilograms
born/ewes conceived (Abdel-Mageed and Abd El-Gawad, 2015;
González-García et al., 2015).
Although there were more data about the fact that the body condition status
of ewes, especially in the third part of gestation, has a positive effect on
mammary gland regeneration and correspondingly more milk yield after
postpartum and also decreases lamb deaths due to undernutrition of lambs
(Kenyon et al., 2013), there were not enough data related to the influences
of BCS, parity and live body weight at mating on litter size, return rate and
fecundity. Therefore, in this study, we aimed to determine the effect of BCS,
parity and body weight of Karayaka ewes, partly reared under extensive
conditions, at mating time on litter size, fecundity, lamb birth weight, the
number of cycles for conception in each mating periods, conception rates and
gestation length.
Materials and methods
All experimental procedures and animal management were performed according
to the Animal Care and Use Guidelines of Ondokuz Mayis University of Local
Ethical Committee.
Data set
In the present study, a total of 284 data collected from Karayaka ewes
(2–6 years old, first to fifth parity) in 2002 (74 heads), 2003 (85 heads)
and 2004 (125 heads) raised at the experimental farm (41∘35 N) of
the Ondokuz Mayis University, Samsun, Turkey. Furthermore, a total of
290 data were collected from lambs in 2002 (77 heads), 2003 (88 heads) and
2004 (125 heads). The ewes were divided on the basis of their BCSs into four
groups: thin, (BCS =≤ 2.0; n= 70 (at mating) and n= 38 (at
postpartum)), medium (BCS = 2.5–3.0; n= 122 (at mating) and 142 (at
postpartum)), fat (BCS = 3.5–4.0 n= 72 (at mating) and 59 (at
postpartum)), and very fat BCS => 4.0; n= 20 (at mating) and 17
(at postpartum)) at mating time in breeding season and at postpartum within
at least 6 h after the expulsion of fetal membranes (on a scale of 1 to 5, 1
is emaciated and 5 is extremely fat; the scale has increments of 0.5)
(Gallego-Calvo et al., 2014). Thin and very fat groups were termed extreme
groups.
Body condition scoring was performed by lumbar palpation performed by a
single, skilled person. Body weights of the ewes were determined by weighing
them on scales (±50 g) at mating and postpartum within at least 6 h
after the expulsion of fetal membranes.
All the lambs were weighed at least 6 h after the expulsion of fetal
membranes and ear-tagged after birth, and then pedigree, birth type and
gender were recorded. The number of lambs and the litter size, fertility
rations and gestation lengths of ewes based on BCSs at mating and postpartum
were calculated as the results of lambing in farm records, and return rates
were also determined the same way.
Table 1 summarizes the ewe live weights and body condition scores at the
beginning of mating periods and at term periods. The herd body condition
frequencies are shown in Fig. 1.
In lambing periods, ewes were observed more than once daily and the lambing
ewes were separated from the herd and housed in individual lambing pens. The
genders, birth types, birth weights and mother ear numbers, etc., related to
the bearing lambs were recorded. Lambing difficulty was assessed according to
the method suggested by Dawson et al. (1999).
Parities were determined from the ear-tagged records in the farm pedigree
record lists.
The distribution of ewe number and percentage according to BCS at
mating.
Body condition scores and body weight status of ewes in three
consecutive years.
EMA: ewe mean age. EBWM: ewe body weight at mating. EBWP: ewe
body weight at postpartum. GL: gestation length. EBCSM: ewe body condition
scores at mating. EBCSP: ewe body condition score at postpartum. LBW: lamb
birth weight. NS: not significant. a, b Values with different
superscript are significantly different in each column.
Animal management
Throughout the year, the ewes were maintained on pasture if weather
conditions were suitable. However, the ewes were given grass hay
(approximately 1500 g, per animal per day, containing 7.5 % crude
protein (CP), 7.3 J ME/kg DM joules of metabolizable energy per kilogram
of dry matter) and compound feed (approximately 350 g, per animal per day,
containing 16.3 % CP, 12.5 MJ ME/kg DM) under inadequate pasture
during the last 2 months of their gestation. Water and mineral blocks
containing trace elements and vitamins were supplied ad libitum.
Lambs were separated from their mothers 2 months before mating and ewes were
dried out. The ratio of replacement in the herd was approximately
20–25 %. Ewes were maintained in the herd for five parities.
Rams were selected from the same private Karayaka sheep flocks and they were
kept separately from ewes during the breeding season. A ram was used as a
breeder for at most 2 years. Breeding rams of 3–4 years old (five heads per
year) and teaser rams of 2–5 years old (five heads per year) were fed 450 g
concentrate feed and hay grass (ad libitum) during the mating periods. All of
the necessary vaccinations, external and internal parasite treatments were
routinely performed by the official veterinary in the farm.
Matings
Mating was performed each year for 51 days during October and September
(approximately three estrus cycles). Teaser rams were used at a ratio of
1/15 to evaluate estrus twice daily: in the morning at 06:30 and
08:00 local time (LT) and in the evening 18:30 and 20:00 LT in September to
October. Ewes within each BCS groups were assigned to rams randomly each
year. The estrus ewes determined by the teaser rams were kept in single-sire
pens for mating for at least 9 h. After mating, all ewes were stained with
red or blue dye so that they were recognized easily for their further estrus
return states and all events were recorded. Lamb births took placed within
approximately 35 days in each year.
Statistical analyses
No significant differences among the variables (BW and BCS at mating and
postpartum) and years were detected; therefore, data were combined. There was
a sizeable correlation (R=0.996, P< 0.0001) between ewes' parity and
ewes' age. Therefore, ewe parity was used instead of ewe age (Kenyon and
Blair, 2014). Fertility rate, fecundity, return rate, incidence of dystocia
and litter size (prolificacy) were assessed by χ2 test. Binary logistic
regression analysis was used to determine of the effect of BCS, parity and
ewe weight at mating on fertility and lamb yield. The correlation and
regression procedures were used to determine multiple correlation
coefficients between lamb birth weight and ewe age, ewe BCS and ewe BW at
postpartum. The data of ewe BWs and lamb birth weight were analyzed with a
general linear model. The Duncan multiple comparison test was used to
determine the differences between means. All statistical evaluations were
performed using the SPSS software package version 24.0 for Windows (IBM SPSS
Inc, 1989–2016). All tests were conducted at the P< 0.05 level of
significance. The ± values given after the numbers represent the standard
error of the mean.
Results
Figures 1 and 2 show the distributions of ewes in herds according to their
BCSs at the time of mating and postpartum, respectively. The BCS and BWs of
ewes related to years are given in Table 1. The lowest and the highest BCS
were determined as 1.5 and 5.0 in the herd. Overall, 24.7 and 7.1 % of
ewes at mating period and 14.8 and 6.7 % of ewes at postpartum period
were in the thin and very fat BCS groups, respectively. Overall, 68.2 %
of ewes were in the medium and fat BCS groups at mating and 78.5 % were
in these groups at postpartum (Figs. 1 and 2).
The ratio of very thin (BCS ≤ 1.5, 5.3 %) to very fat (BCS ≥ 4.5, 7.1 %) groups was low in the flock at mating
time. The BCS means at mating and
postpartum were 2.93 and 2.90, respectively. This indicates that the
nutrition level of herds is adequate. The ratio of ewes with BCSs below 1.5
and of very fat ewes was 3.1 and 6.7, respectively (Fig. 2). There were
significant (P< 0.01) differences between lamb birth weights related
to years.
The distribution of ewe number and percentage according to BCS at
postpartum.
Binary logistic regression was used to determine the effect of BCS and parity
on fertility. The BCS and parity affected fertility (P< 0.05). Lamb
yield increased 60 % when BCS ≥ 3; in any case, the effect of
parity was found to be insignificant. An increase of 1 kg in the weight of
ewes at mating led to a 5 % increase in fertility, but this increase was
found to be meaningless (P> 0.05).
The relationship between the body weight, gestation length and BCS at mating
time and the factors such as year and the age of ewes were not significant
(P> 0.05, Table 1). The BCS at mating had a significant effect on
fertility rate, gestation length, live weight of ewes at both mating and
postpartum, twinning, ewe body condition score (EBCS) at postpartum
(P< 0.01) and return rate (P< 0.05) (Table 2). Similarly, the
effects of parity on BCS, infertility, ewe body weight changes, fecundity
(P< 0.01) and ewe live weight at mating and postpartum, lamb birth
weight, gestation length were significant (P< 0.05; Table 3).
The effects of body condition scores on reproductive performance of
ewes at mating.
EBWM: ewe body weight at mating. GL: gestation length. EBWP: ewe
body weight at postpartum. BCSM: body condition scoring at mating. LBW: lamb
birth weight. N: number of mating. n: number of mating ewes.
a, b, c Values with different superscript are significantly
different in each row.
The distributions of body weight, body condition scores, litter size
and lamb birth weight of ewes according to parity.
EBWM: ewe body weight at mating. EBWP: ewe body weight at
postpartum. EBCSM: ewe body condition score at mating. EBCSP: ewe body
condition score at postpartum. EBWC: ewe body weight changes between mating
and postpartum according to ewe parity. n: number of mating ewes. GL:
gestation length. LBW: lamb birth weight. a, b, c, d Values with
different superscript are significantly different in each line.
The overall body weights of ewes at postpartum were approximately 2.20 kg
higher than their body weights at mating time (Table 4). Lamb birth weights
were not affected by their mothers' body weights and BCSs at mating, but a
significant relationship was found between lamb birth weight and ewe body
weight at postpartum (R=0.130, P< 0.05), between lamb birth weight
and ewe BCS at postpartum (R=0.486, P< 0.01), and between lamb birth
weight and ewe parity (R=0.142, P< 0.05) at postpartum. With
increasing ewe body weight and ewe BCS at postpartum (during the gestation
period), lamb birth weight increased
(Y=3.432± 0.10 + 0.130 ± 0.047EBCS, P< 0.01;
Y=2.922± 0.42 + 0.0178EBW ± 0.009, P< 0.05). There
was a positive correlation between the mating body weight and postpartum body
weight of ewes (R=0.844, P< 0.01). Although the number of the ewes
exposed to dystocia is low in the herd, one ewe in the thin BCS group and
three ewes in the very fat BCS group had dystocia. The difference in the
incidence of dystocia between these groups was found to be significant
(P< 0.0001).
Body weights, gestation lengths and lamb birth weights of ewes
related to BCS at postpartum.
EBCSP: ewe body condition score at postpartum. EBWP: ewe body
weight at postpartum. LBW: lamb birth weight. GL: gestation length. n:
number of mating ewes. a, b, c Values with different superscript
are significantly different in each column.
Fecundity was determined as 0.86, 1.04, 1.13 and 1.10 for the BCS groups.
Litter size or prolificacy related to ewe body condition scores in the four
groups was determined as BCS = 1.5–2.0, 1.05 ± 0.033; BCS
2.5–3.0, 1.11 ± 0.031; BCS 3.5–4.0, 1.19 ± 0.055; and BCS
4.5–5.0, 1.29 ± 0.140. The fertility rates of thin and very fat groups
were lower (P< 0.01) than those of medium and fat groups (Table 2).
At mating, the fertility rate, litter size and fecundity were higher in
moderate (medium + fat groups) than extreme groups (thin + very fat
groups) (χ2=10.607, P< 0.01). The BCSs and body weights of
ewes at postpartum are formed as a result of feeding management during the
gestation period. While the litter size increases (P< 0.05), the
infertility decreases (χ2=12.282; P≤0.013) with increasing
parity (Table 3).
Discussion
In this study it was intended to investigate the effects of different BCSs at
mating and parities in a state farm herd on fertility, return rate, gestation
length and lamb birth weight by using farm records.
Some differences were observed in BCSs between animals reared under the same
management conditions. BCS was influenced by both genetical and environmental
factors (Abdel-Mageed and Abd El-Gawad, 2015). The differences between the
body conditions scores of ewes in this study could be attributed to their
status within the hierarchy of the herd, competition among them and
physiological differences (milk yield levels, suckling and having twin lamb)
(Gonzáles-García et al., 2015). A BCS above 2.5 is recommended at
mating (Thompson and Meyer, 1994; Yilmaz et al., 2011; Vatankhah et al.,
2012; Van-Burgel et al., 2011). The BCS values of ewes determined in the
present study are in accordance with this recommendation (68.2 % of ewes
were in the medium and fat BCS groups; Table 2 and Fig. 2). On the other
hand, it is difficult to maintain the ewes at a stable BCS under extensive
rangeland rearing conditions due to the difficulty regarding individual
nutrition of ewes under these conditions. Our study also showed that BCSs
less than 2.5 and higher than 4.0 had a negative effect on fertility rate. It
was not only lower BCSs but also higher BCSs that had a harmful effect on
fertility rate in this study. There are several possible reasons for the
lower fertility rate in the thin and very fat group's ewes. However, the most
likely reason
is that the gonadotropin hormone releasing mechanism in thin and very fat
ewes could be affected by the body energy reserves of ewes (Catunda et al.,
2013; Boudreau et al., 2014), which has been found to lead to a decrease in
the number of follicles (Faddy, 2000). Meyer (2002) reported that poor BCSs
have adverse effects on uterine efficiency, ovulation rate and embryo yield.
In the light of this knowledge, we could say that our result from the thin
group is in accordance with these findings and, additionally, that a very fat
state has a similar effect on fertility.
In our study medium and fat body condition groups had a higher prolificacy
and fecundity at mating than thin and very fat groups. According to some
studies, the ovulation rate is not influenced by the BCS of ewes (Mitchell et
al., 1996; Diskin and Moris, 2008). Our findings can be attributed to the
fact that medium and fat groups in our study had a good physiological and
balanced endocrine profile so that shedding ova might reside in a suitable
uterus environment and be implanted into it. On the other hand, parity, BCS
and body weight affected each other (Faddy, 2000; Meyer, 2002). Thus, the
difference in fecundity and prolificacy cannot be attributed to only one of
these factors. Additionally, there are many reports that ovulation rate and
litter size were influenced by ewe BW, parity and BCS (Michels et al., 2000).
It was reported in some studies (Michels et al., 2000; Yilmaz et al., 2011;
González-García and Hazard, 2016) that parity has a strong effect on
fecundity and prolificacy or litter size in sheep farming.
The present study showed that animal body fat reserves can affect the return
rate and fecundity of ewes. The return rate might be affected by fertility
failure or early embryonic deaths for reasons relating to physiological,
endocrine and environmental factors (Diskin and
Morris, 2008; Catunda et al., 2013). The BCS or body fat reserves are
significant effective factors affecting reproductive performance, especially
altering or regulating basic hormones that affect the ovulation rate,
fertility, and the implantation and maintenance of gestation (Catunda et al.,
2013; Boudreau et al., 2014; González-García et al., 2015).
The birth weight of lambs of multiparous ewes was higher than those of
primiparous ewes. This finding is agreement with the findings of many
researchers (Kenyon and Blair, 2014; González-García et al., 2015;
González-García and Hazard, 2016; Griffiths et al., 2016). The
lighter birth weights of lambs born to primiparous ewes compared to
multiparous ewes can be explained by the fact that the uterus environment of
primiparous dams was not fully developed, especially with regard to size
(González-García et al., 2015). As a matter of fact, there are many
reports about the birth weight differences favoring lambs born to multiparous
ewes, and this continues to weaning time
(Corner et al., 2013; González-García and Hazard, 2016). On the
other hand, it is known that the birth weights of lambs affect BWs and BCSs
of ewes at postpartum. The birth weight of lambs is sensitive to a variety of
influences (parity, maternal BCS, gestation length, etc.) (Sharma et al.,
2012; Griffiths et al., 2016).
Additionally, it is known that a fetus gains most of its weight during the
last 2 months of gestation (McGregor, 2016; Ahmed et al., 2016). The
gestation length of primiparous ewes was lower than those of
multiparous ewes. This might explain
why lambs born to first-parity ewes have a lower birth weight. On the other
hand, higher BWs and BCSs during this period might have positive effects on
uterine and ovary effectiveness (Meyer, 2002) and the very fat ewes generally
give birth to heavier lambs. However, this situation also increases the
incidence of dystocia events (Ocak et al., 2005).
In the present study, an increased tendency of dystocia in thin and very fat
groups was observed. The incidence of dystocia in the herd was low
(1.95 %), and the highest dystocia incidence determined in the different
groups was as follows: thin group – 2.63 %; medium group – 0.00 %;
fat group – 1.69 %; and very fat group –
17.65 %. This
increased tendency can be attributed to weaknesses of lambs in the weak group
and the very fat condition of lambs in the very fat group. The higher
incidence of dystocia in animals with high BCS (P< 0.05) can be
attributed to the fact that the fat layer surrounding the birth canal does
not allow muscles to relax. The very fat state might lead to endocrine
disorders (Kenyon and Blair, 2014; Fthenakis et al., 2015; Tripathi et al.,
2016).
Body condition of an animal varies depending on breed, its health state,
yield level, yield type, physiological state, environmental conditions and
genetical state (Yilmaz et al., 2011; Abdel-Mageed and Abd El-Gawad, 2015).
The presence of animals with different BCSs in a herd is normal. The
percentages of animals with different BCSs partly depends on the quality of a
rangeland's vegetation and the possibilities of supplying compound feed.
The higher incidence of return rates of ewes in weak and very fat groups
might be associated with conceptus problems. These results show that both
overfeeding and underfeeding of animals lead to negative effects on
fertility. The litter size (the number of lambs born per lambing ewe) of
primiparous ewes has been found to be lower than that of multiparous lambing
ewes. The result is in agreement with the finding of Dwyer et al. (2005) and
Luridiana et al. (2015). The number of lambs born to a mating ewe throughout
her life and the number of lambs born to a ewe at a given
birth were affected by BCS and parity. It
was reported that there was a strong relationship between age and parity in
dams in livestock animals (Kenyon and Blair, 2014).
Conclusion
This study showed that the highest reproductive performances were observed
for ewes with BCSs of 2.5 or 4.0. In the present study, it was shown that BCS
had minimal effects on birth weights of lambs. Furthermore, the incidence of
dystocia was shown to increase in extreme (thin and very fat) groups.
Data are available from the corresponding author
upon request.
The authors declare that they have no conflict of interest.
Acknowledgements
The authors would like to thank the OMU Agricultural Research and Application
Farm staff for animal care and data recording.
Edited by: Steffen Maak Reviewed by: three
anonymous referees
References
Ahmed, M. H., Salem, A. Z. M., Olafadehan, O. A., Kholif, A. E., Rivero, N.,
Mariezcurrena, M. A., Camacho, L. M., Elghandour, M. M. Y., Alonso, M. U.,
and Almaz, A. H. A.: Effect of pre- and post-partum dietary crude protein
level on the performance of ewes and their lambs, Small Ruminant Res., 136,
221–226, 2016.
Abdel-Mageed, I. I. and Abd El-Gawad, M. H.: Effects of breed, parity and
post-mating nutrition on reproductive wastage and pregnancy outcomes of
Egyptian sheep, Small Ruminant Res., 130, 171–177, 2015.
Boudreau, L., Benkel, B., Astatkie, T., and Rouvinen-Watt, K.: Ideal body
condition improves reproductive performance and influences genetic health in
female mink, Anim. Reprod. Sci., 145, 86–98, 2014.
Cam, M. A., Olfaz, M., and Soydan, E.: Body measurements reflect body weights
and carcass yields in Karayaka sheep, Asian J. Anim. Vet. Adv., 5,
120–127, 2010.
Cam, M. A., Olfaz, M., Kirikci, K., Garipoglu, A. V., and Soydan, E.: Market
productivity of single and twin bearing Karayaka Ewes, Academia J.
Biotechnol., 5, 84–90, 2017.
Catunda, A. G. V., Lima, I. C. S., Bandeira, G. C., Gadelha, C. R. F.,
Pereira, E. S., Salmito-Vanderley, C. S. B., Araújo, A. A., Martins, G.
A., and Campos, A. C. N.: Blood leptin, insulin and glucose concentrations in
hair sheep raised in a tropical climate, Small Ruminant Res., 114, 272–279,
2013.
Corner, R. A., Mulvaney, F. J., Morris, S. T., West, D. M., Morel, P. C. H.,
and Kenyon, P. R.: A comparison of the reproductive performance of ewe lambs
and mature ewes, Small Ruminant Res., 114, 126–133, 2013.
Corner-Thomas, R. A., Hickson, R. E., Morris, S. T., and Kenyon, P. R.: The
influences of live weight and body condition score of ewe lambs from breeding
to lambing on the live weight of their singleton lambs to weaning, Small
Ruminant Res., 119, 16–21, 2012.
Dawson, L. E. R., Carson, A. F., and Kilpatrick, D. J.: The effect of
digestible undergradable protein concentration of concentrates and protein
source offered to ewes in late pregnancy on colostrum production and lamb
performance, Anim. Food Sci. Technol., 82, 21–36, 1999.
Dwyer, C. M., Calvert, S. K., Farish, M., Donbavand, J., and Pickup, H. E.:
Breed, litter and parity effects on placental weight and placentome number,
and consequences for the neonatal behaviour of the lamb, Theriogenology, 63,
1092–1110, 2005.
Diskin, M. G. and Moris, D. G.: Embryonic and early foetal losses in cattle
and other ruminants, Reproduction Domestic Anim., 43, 260–267, 2008.
Faddy, M. J.: Follicle dynamics during ovarian ageing, Mol. Cell Endocrin.,
163, 43–48, 2000.
Fthenakis, G. C., Mavrogianni, V. S., Gallidis, E., and Papadopoulos, E.:
Interactions between parasitic infections and reproductive efficiency in
sheep, Vet. Parasitol., 208, 56–66, 2015.
Gallego-Calvoa, L., Gatica, M. C., Guzmána, J. L., and Zarazaga, L. A.:
Role of body condition score and body weight in the control of seasonal
reproduction in Blanca Andaluza goats, Anim. Reprod. Sci., 151, 157–163,
2014.
González-García, E. and Hazard, D.: Growth rates of Romane ewe lambs
and correlated effects of being mated as hoggets or two-tooth ewes on first
offspring performance, Livest. Sci., 189, 63–69, 2016.
González-García, E., Tesniere, A., Camous, S., Bocquie, F.,
Barillet, F., and Hassoun, P.: The effects of parity, litter size,
physiological state, and milking frequency on the metabolic profile of
Lacaune dairy ewes, Domestic Anim. Endocrin., 50, 32–44, 2015.
Griffiths, K. J., Ridler, A. L., Heuer, C., Corner-Thomas, R. A., and Kenyon,
P. R.: The effect of liveweight and body condition score on the ability of
ewe lambs to successfully rear their offspring, Small Ruminant Res., 145,
130–135, 2016.
Hocking, E. J. E, Copping, K. J., and Thompson, A. N.: Managing the nutrition
of twin-bearing ewes during pregnancy using Lifetime wool recommendations
increases production of twin lambs, Anim. Prod. Sci., 51, 813–820, 2011.
IBM SPSS Inc: Statistical Package for the Social Sciences, Chicago, IL,
1989–2016.
Kenyon, P. R. and Blair, H. T.: Foetal programming in sheep – Effects on
production, Small Ruminant Res., 118, 16–30, 2014.
Kenyon, P. R., Morris, S. T., Hickson, R. E., Back, P. J., Ridler, A. L.,
Stafford, K. J., and West, D. M.: The effects of body condition score and
nutrition of triplet-bearing ewes in late pregnancy, Small Ruminant Res.,
113, 154–161, 2013.
Keinprecht, H., Pichler, M., Pothmanna, H., Huber, J., Iwersena, M., and
Drillicha, M.: Short term repeatability of body fat thickness measurement and
body condition scoring in sheep as assessed by a relatively small number of
assessors, Small Ruminant Res., 139, 30–38, 2016.
Luridiana, S., Mura, M. C., Daga, C., Farci, F., Di Stefano, M. V., Zidda,
F., and Carcangiu, V.: Melatonin treatment in spring and reproductive
recovery in sheep with different body condition score and age, Anim. Reprod.
Sci., 160, 68–73, 2015.
McGregor, B. A.: The effects of nutrition and parity on the development and
productivity of Angora goats: 1. Manipulation of mid pregnancy nutrition on
energy intake and maintenance requirement, kid birthweight, kid survival, doe
live weight and mohair production, Small Ruminant Res., 145, 65–75, 2016.
Meyer, H. H.: Genetic and Environmental Impacts on Prenatal Lamb Loss, Sheep
Goat Res. J., 17, 11–14, 2002.
Michels, H., Decuypere, E., and Onagbesan, O.: Litter size, ovulation rate
and prenatal survival in relation to ewe body weight: genetics review, Small
Ruminant Res., 38, 199–209, 2000.
Mitchell, L. M., King, M. E., Aitken, R. P., and Wallace, J. M.: Effect of
mating season and body condition on ovulation, fertilization and pregnancy
rates in crossbred ewes, Theriogenology, 45, p. 293, 1996.Ocak, N., Cam, M. A., and Kuran, M.: The effect of high dietary protein
levels during late gestation on colostrum yield and lamb survival rate in
singleton-bearing ewes, Small Ruminant Res., 56, 89–94, 2005.
Roche, J. R., Friggens, N. C., Kay, J. K., Fisher, M. W., Stafford, K. J.,
and Berry, D. P.: Body condition score and its association with dairy cow
productivity, health, and welfare, J. Dairy Sci., 92, 5769–5801, 2009.
Sharma, R. K., Blair, H. T., Jenkinson, C. M., Kenyon, P. R., Cockrem, J. F.,
and Parkinson, T. J.: Uterine environment as a regulator of birth weight and
body dimensions of newborn lambs, J. Anim. Sci., 90, 1338–1348, 2012.Thompson, J. M. and Meyer, H.: Body condition scoring of sheep, available at:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/14303/ec1433.pdf
(last access: 22 February 2018), 1994.
Tripathi, S. K., Farman, M., Nandi, S., Mondal, S., Gupta, P. S. P., and
Grish, K. V.: In vitro culture of oocytes and granulosa cells collected from
normal, obese, emaciated and metabolically stressed ewes, Anim. Reprod. Sci.,
170, 83–89, 2016.
Van Burgel, A. J., Oldham, C. M., Behrendt, R., Curnow, M., Gordon, D. J.,
and Thompson, A. N.: The merit of condition score and fat score as
alternatives to live weight for managing the nutrition of ewes, Anim. Prod.
Sci., 51, 834–841, 2011.
Vatankhah, M. and Salehi, S. A.: Genetic and non-genetic factors affecting
Lori-Bakhtiari ewe body weight and its relationship with productivity, Small
Ruminant Res., 94, 98–102, 2010.
Vatankhah, M., Talebi, M. A., and Zamani, F.: Relationship between ewe body
condition score (BCS) at mating and reproductive and productive traits in
Lori-Bakhtiari sheep, Small Ruminant Res., 106, 105–109, 2012.
Yilmaz, M., Altin, T., Karaca, O., Cemal, I., Bardakcioğlu, H. E.,
Yilmaz, O., and Taskin, T.: Effect of body condition score at mating on the
reproductive performance of Kivircik sheep under an extensive production
system, Tropical Animal Health Production, 43, 1555–1560, 2011.