In order to verify the oestrus activity and to observe the body weight of Saanen goats, when reared in intensive condition of Northeast Brazil during four different seasons, ten adult Saanen goats were used. In this experiment four climatic seasons were considered; early rainy (ER), late rainy (LR), early dry (ED) and late dry (LD). Oestrus behaviour was monitored twice a day (8:00 a.m. and 4:00 p.m.) during all the experiment, using two vasectomised bucks. The oestrus cycles were quantified within each season and classified as short (< 17 days), normal (17-25 days) or long (> 25 days). The goats were weighed every seven days.
During the late rainy season, a significant fall of the mean body weight of the animals was observed when compared to early rainy season. A larger percentage of goats in oestrus were observed during the late rainy season. Oestrus duration was longer in the late rainy and early dry season than in early rainy and late dry season. During the experiment, there were 12.0% of short cycles, 50.3% of normal cycles and 37.7% of long cycles. The percentages of abnormal cycles (short and long cycles), in relation to total cycles monitored in each season were 52, 58, 38 and 50% for early rainy, late rainy, early dry and late dry, respectively.
results of this study it can be concluded that pen-fed Saanen goats do not show
seasonality for oestrus behaviour. Rainfall appeared to be an extero-receptive
factor influencing the quality of sexual activity and performance in these goats.
Brazil has 1.18% of the world goat population (FAO 2000) with 94% of them in the
Northeast region, confirming the great significance of
this region for goat production (IBGE
In northeast of
Brazil there is no clear policy for evaluating the local genotypes and
little appreciation of their potential. Thus emphasis has been on the importation of specialized
breeds, such as the Saanen, French Alpine and Toggenburg, the Anglo-nubian and Boer, which are maintained in their genetic
purity or used in crossings with local goat breeds. The Saanen
breed is the milk breed most widely used in the world for milk production and there are quite large
numbers in Brazil (Ribeiro 1997). There are reports of Saanen goats, exploited in the tropics, with exceptional production, such as the 3,084 kg
in 305 days of an Australian goat (Sands and McDowell 1978), confirming the productivity potential ability of this breed in the tropics. A
Alpine breeds originated in temperate countries, where they present sexual activity limited to a certain time of the year (Shelton 1978; Ortavant et al 1985; Chemineau et al 1992). In contrast, the native breeds of Northeast Brazil show sexual activity during the whole year (Silva Neto 1948; Simplício 1985; Simplício et al 1986). Therefore, the objective of this work was to verify the oestrous activity and to observe the body weight change of Saanen goats, reared intensively during four different seasons in tropical Northeast Brazil .
The experiment was carried out from April of 1998 to March of 2000 in the State
University of Ceará, Fortaleza, which is located at 3o 43'47 '' South and 38o
30'37 '' West. The variation of photoperiod in this location is
only 16 min between the solstices of the summer and winter.
The region where the experiment was carried out is
tropical and is characterized by small variation in annual
temperature (26 to 28o C). The highest rainfall is observed from January to June (FUNCEME 2000) (Figure 1).
In this experiment four climatic seasons were considered , which were described by Kronberg and Malechek (1997) as:
Ten adult Saanen goats were obtained from a private farm in
Fortaleza, where the conditions were similar
to those in the experimental location They were 15.6 ± 7.6 months old at the start of the experiment. In order to verify any reproductive disorder, ultrasonic
examinations (Shimasonic, 3 MHz probe) were performed monthly during the experiment.
Oestrus behaviour was monitored twice daily (8:00 a.m. and 4:00 p.m.) using two vasectomized bucks. Immobilization of the female when mounted by the male was considered to be a sign of occurrence of oestrus (Mauléon and Dauzier 1965). The number of oestrus cycles, as well as the length, were recorded during each season.The oestrous cycles were classified as short (< 17 days), normal (17-25 days) or long (> 25 days) (Chemineau et al 1992).
All calculations were performed
with the GLM of the SAS statistical programme (SAS 1995). Length of cycle (d), length of oestrus (h) and
body weight (kg) were submitted to two-way
analysis of variance. The data of length of cycle and length of oestrous were
transformed in log x. The following model of ANOVA was used:
yij = µ + ai +
ßj + eij
Yi j = observation;
µ = mean;
ai = effect of individual i;
ßj = effect of seasons j (j= ER, LR, ED, LD);
ei j = error term eij
Differences between means of body weights were identified by the Duncan test. Comparison between percentages was performed by Chi Square test. Results were expressed as mean± SEM and differences were taken as statistically significant at P<0.05.
Therainfall in Fortaleza during the experimental period was similar to the mean monthly value for 30 years (1961-1990), indicating that the experimental period was representative of the climate for this area. Two different seasons were identified, which present a length of six months each: rainy (from January to June) and dry (from July to December).
Figure 1: Mean
monthly rainfall (mm) in Fortaleza during the early rainy (ER), late rainy (LR), early dry
and late dry (LD) season from 1998 to 2000 (this experiment) and from 1961 to 1990 (FUNCEME 2000).
During the late rainy season, there was a significant decrease of the mean body weight of the animals when compared to the early rainy season (P < 0.05). During the early dry and late dry seasons, an increase (P<0.05) of body weight was observed (Figure 2).
Figure 2: Body weight
(mean ± SEM) of Saanen goats during the early rainy (ER),
late rainy (LR), early dry (ED) and late dry (LD) season
It was observed that all the goats showed oestrus behaviour throughout the experiment. However,
a larger percentage of goats in oestrus was observed during the
late rainy season (P<0.05), while in the other seasons the
percentage never exceeded 40% (Figure 3).
Figure 3: Mean percentage of Saanen goats in
oestrus, explored in tropical area,
during the early rainy (ER), late rainy (LR), early dry (ED) and late dry (LD) season
(ab: Different letters among seasons indicate a difference at P < 0.05)
Table 1: Mean and SEM for length of oestrus (hours) and length of oestrus cycles in the different seasons
Length of oestrus, hours
26.7 ± 2.54
34.9 ± 2.78
37.1 ± 3.48
28.4 ± 2.80
32.5 ± 4.34
33.2 ± 2.75
36.0 ± 3.45
37.6 ± 3.44
Length of cycle, days
18.3 ± 0.36
19.3 ± 0.3
19.6 ± 0.22
19.2 ± 0.53
The minimum length of oestrus found in the
experiment was 6h and the maximum 144 h. Season
had no apparent effect on the duration of oestrus nor on the length of the oestrus cycle (Table 1). The mean length of oestrus for
normal cycles, during the experiment, was 34.5 ± 1.69 h. The mean length of normal oestrus cycles was
The mean length of normal oestrus cycles was19.1 ± 0.35 days.
Alarger percentage of short cycles was observed in the late rainy season (P<0.05), when compared to the other seasons (Figure 4). Within the late rainy season, there were no differences in the percentages of short, normal and long cycles. In other seasons there were higher percentages of normal and long cycles compared to the short cycles (P<0.05). The minimum length of short cycle found was 2d and of long cycle was 305d.
Figure 4: Mean percentage of short, normal and
long oestrous cycles of Saanen goats,
during the early rainy (ER), late rainy (LR), early dry (ED) and late dry (LD) season.
ab Different small letters among types of cycles within seasons indicate difference (P<0.05).
AB Different capital letters for each type of cycle among seasons indicate difference (P < 0.05).
In tropical areas and below 25o latitude, the animal production is dependent
on the forage availability throughout the year
(Martin et al 1999). Overall, in the Northeast part of Brazil
and during the rainy season there is abundance of forage, while
during the dry season, the forage is scarce and fibrous and, consequently, of low quality
(Lindsay et al 1993).
The dry season in tropical areas is characterized by the low nutritive value of the natural forage. However,
the body weight of the goats in this
study increased in the dry season. In goats reared under grazing conditions, the browsing ability and the
characteristic of selecting the most nutritious parts of the plant allow them to change
their diet according to seasonal availability and growth rate of plants, and to increase
their dietary protein intake during dry periods (Louca et al 1982).
Seasonality of reproduction is a common feature in goat breeds of temperate latitudes,
as well as animals of the Saanen breed, and photoperiod seems to be the key factor
controlling reproduction in these areas (Shelton 1978; Ortavant et al 1985; Delgadillo
1990; Chemineau et al 1992). However, under tropical conditions, where the amplitude of
photoperiodic changes is lower, it is known that local breeds of goats are either
non-seasonal breeders or exhibit only a weak seasonality of reproduction (Chemineau 1986;
Simplício 1985). In this experiment, it was observed that the
highest rate of oestrus was in the late rainy season, which is characterized by the
In goats, the oestrus length is approximately 36 hours (Phillips et al 1943; Mishra and
Biswas 1966; Prasad and Bhattacharyya, 1979; Bliss 1980). Chemineau et al (1992) found a
mean length of 30 hours, for oestrus in Alpine goats submitted to the temperate and
tropical photoperiodic regimens. These data are in according with the results observed in
The high percentage of short cycles recorded
in the late rainy season was also reported by Cerbito et
al (1995) and Chemineau (1982), as being related to climatic factors, which act
as important cues in the reproduction of goats. Cerbito
et al (1995), working with native goats of Philippines, observed a
negative correlation between the length of the oestrous cycle and the rainfall. The
authors reported that a 76% increase in the rainfall corresponded to
a decrease in the same proportion in the length of the oestrus cycles.
Despite the high percentage of oestrus observed during the late rainy season, this fact cannot be related to a better reproductive activity, because during this season it was observed the largest percentage of abnormal cycles, mainly of short cycles. The short cycles in goats are related to poor ovulation quality (Camp et al 1983). Thus, we cannot translate the high percentage of oestrus verified in the late rainy season as a parameter of good fertility nor of good reproductive performance. The loss in body weight during the late rainy season could be the factor related to poor reproductive performance.
From the results of this study it can be concluded that pen-fed Saanen goats do not show seasonality for oestrus behaviour when raised in Northeast of Brazil. Rainfall appeared to be an extero-receptive factor influencing the quality of sexual activity and performance in these goats. Thus, goat-breeding programs in Brazil under intensive management could benefit from more extensive use of Saanen goats due to the minimal seasonal effects on reproduction.
E L 1980 Dairy goat reproductive management. Dairy Goat Journal 58:12-13.
Camp J C, Wildt D E, Howard P K, Stuart L D
and Chakraborty P K 1983 Ovarian activity during normal and abnormal length oestrous
cycles in the goat. Biological Reproduction 28:673-681.
Cerbito W A, Natural N G, Aglibut F B and
Sato K 1995 Evidence of ovulation in goats (Capra hircus) with short oestrous cycle
and its occurrence in the tropics. Theriogenology, 43:803-812.
Chemineau P 1982 Reproductive
performance in a creole meat goat flock at three mating periods. In:
Proceedings of Third International Conference on Goat Production and Disease, Tucson,
1982. Abstract. Arizona, :162-174.
Chemineau P, Daveau A, Maurice F and
Delgadillo J A 1987 Effects of tropical photoperiod on sexual activity of Alpine
goats. In: Proceedings of Fourth Conference On Goats, Brasília, 1987. Abstract. Brazil:
Chemineau P 1986 Sexual behaviour and
gonadal activity during the year in the tropical Creole meat goat. I Female oestrous
behaviour and ovarian activity. Reproduction, Nutrition, Developpement 26:441-452.
Chemineau P, Daveau A, Maurice F and
Delgadillo J A 1992 Seasonality of oestrus and ovulation is not modified by subjecting
female Alpine goats to a tropical photoperiod. Small Rum. Research 8:299-312.
Delgadillo J A 1990 Abolition des
variations saisonnières de lactivité sexuelle chez le bouc par des traitements
photopériodiques. Doctoral Thesis, Montpellier, France. 119p.
Eiamvitayakorn J 1986 Aberrant oestrous
cycles in the goat (Capra hircus). MSc Thesis, Laguna, Philippines.
FAO 2000 Statistical database.
2000 Fundação cearense de meteorologia e recursos hídricos. www. funceme.br.
Gonzalez S C and Bury N
M 1982 Sexual season and oestrous cycle of native goats in a tropical zone of
Venezuela. In: Proceedings of International Congress of Goat Production and Diseases,
1982. Abstract. Venezuela: 311.
Hesselink J W 1993 Incidence of hydrometra in dairy goats. Veterinary
1996 Anuário Estatístico do Brasil. Rio de Janeiro:
Knights M and Garcia G W 1997 The
status and characteristics of the goat (Capra hircus) and its potential role as a
significant milk producer in the tropics: a review. Small Ruminant Research 26:203-215
J E, Kemp B, Bevers M M, Van Oord H A and Taverne M A M 1997 Plasma prolactin, growth
hormone and progesterone concentrations in pseudopregnant, hysterectomized and pregnant
goats. Animal Reproduction Science 49:169-178
Kronberg S L
and Malechek J C 1997 Relationships between nutrition and foraging behaviour of
free-ranging sheep and gots. Journal of Animal Science 75:1756-1763
Lindsay D R,
Martin G B and Williams I H 1993 Nutrition and reproduction. In: Reproduction in
Domesticated Animals. World Animal Science: 459-491
Antoniou T and Hatzipanayiotou M 1982 Comparative digestibility of feedstuffs by
various ruminants, specifically goats. In: Proceedings of Third International Conference
on Goat Production and Disease, Tucson, 1982. Abstract. Arizona: 122-132.
Malan S W
2000 The improved Boer goat. Small Ruminant Research 36:165-170.
Martin G B,
Tjondronegoro S, Boukhliq R, Blackberry M A, Briegel J R, Blache D, Fisher J A and Adams N
R 1999 Determinants of the annual pattern of reproduction in mature male Merino and
Suffolk sheep: modification of endogenous rhythms by photoperiod. Reproduction, Fertility
and Development 11:355-366.
and Dauzier L 1965 Variations de durée de
lanoestrus de lactation chez les brebis de
race Ile-de-France. Annales de Biologie Animale, de Biochimie et de
Mishra H R and Biswas S C 1966 A study
on distribution of oestrus in Deshi goats. Indian J. Dairy Sci., 19:132-144.
Ogebe P O, Ogunmodede B K and McDowell L R
1996 Behavioral and physiological responses of Nigerian dwarf goats to seasonal
changes of the humid tropics. Small Ruminant Research 22:213-217.
Ortavant R, Pelletier J, Ravault J P,
Thimonier J and Volland-Nail P 1985 Photoperiod: main proximal and
distal factor of the circannual cycle of
reproduction in farm animals. In: Oxford Reviews
of Reproductive Biology, Oxford, 1985, England: 305-345.
Phillips R W, Simmons V L and Schott R G
1943 Observations on the normal oestrus cycle and breeding season in goats and
possibilities of modification of the breeding season with gonadotropic hormones. American
Journal of Veterinary Research 4:360.
Prasad S P and Bhattacharyya N K 1979
Oestrous cycle behaviour in different seasons in Barbari nannies. Indian Journal of
Animal Science 49:1058-1062.
S D A 1997 Caprinocultura: Criação racional de caprinos. São Paulo: Nobel, 319p.
Sands M and McDowell R E 1978 The potential of goat for milk production in
the tropics. Cornell Int. Agric. Dep. Anim. Sci., 60. 53p.
SAS 1995 SAS users guide: Statistic, SAS Inst., Cary, NC.
Shelton M 1978 Reproduction and breeding of goats. Journal of Dairy
Silva Neto J M 1948 Primeira
contribuição para o estudo do caprino nacional Moxotó. Sep. Bol.- Secretaria de
Agricultura, Indústria e Comércio do Estado de Pernambuco, 15:1-49.
Simplício A A 1985 Reproduction in
three native genotypes of goats under two feeding management systems in Northeast Brazil;
Progesterone and luteinizing hormone profiles during the oestrous cycle and seasonal
anestrus in Spanish goats in the United States. PhD Thesis, Utah, United States of
Simplício A A, Riera G S, Nunes J F and
Foote W C 1986 Frequency and duration of oestrous cycle and period in genetically
non-descript (SRD) type of goats in the tropical Northeast of Brazil. Pesquisa
Agropecuaria Brasilera, 21:535-540.
Smith M C 1986 The reproductive anatomy
and physiology of the female goat. In: Current Therapy in Theriogenology 2, Philadelphia,
Received 14 July 2001
Received 14 July 2001
Go to top