Effect Of Body Condition Score Research Articles

Effect of Body Condition Score, Live Weight and Age on Reproductive Performance of Afshari Ewes

Effect of Body Condition Score, Live Weight and Age on Reproductive Performance of Afshari Ewes

Some important factors affecting fertility in sheep

Efficiency of sheep production is conditioned by fertility. According to some authors number of offspring obtained per lambing is more important than gain of weight. Genetic relationships involving reproductive traits were seldom studied. Reproductive traits have low heritabilities, a discrete phenotypic expression, and are expressed only in sexually mature ewes leading to low selection intensities and long generation intervals. Documentation of realized selection response is also often complicated by the low heritabilities of fertility traits. Existence of a major gene affecting prolificacy had been suggested and at that time there were many sceptics who strongly doubted that a trait as complex as reproduction could be profoundly influenced by a single gene. Major genes affecting prolificacy in sheep was founded. A mutation in the bone morphogenetic protein 15 gene (BMP15, also known as GDF9B) responsible for high prolificacy in Inverdale sheep had been discovered and evidence of segregating major genes was being reported from flocks around the world. Development of gene mapping techniques, and locating alleles that are responsible for the fertility of sheep began a new chapter in predicting and controlling the fertility of sheep. The beneficial effects of nutrition on reproduction in sheep are well known. This procedure is known as flushing. The effect of Body Condition Score (BCS), before mating, during mating and after mating period, on reproductive efficiency of different breeds of sheep in the different rearing systems were studied. The farm manager has the ability to control or at least to manipulate the factors that have an impact on fertility.

Effect of body condition score at mating on the reproductive performance of Kivircik sheep under an extensive production system

The aim of this study was to determine the effects of the body condition score (BCS) of ewes before and during the mating season on their reproductive performance under an extensive production system. In this study, 240 Kivircik sheep from the flocks of two breeders were used for over a 2-year period. The flocks were fed under extensive conditions on natural pastures throughout the year. The ewes were synchronized in two different periods, one of which was 45 days before the other. Before the introduction of rams to the ewes, the ewes were weighed after measuring their BCS. Detailed records were kept for every flock in each year. We found significant effects of BCS on pregnancy rate, lambing rate (P < 0.05) and fecundity (P < 0.05). The BCS for the highest pregnancy, lambing rate, and fecundity was determined between 2.01 and 3.00, while the lowest rates for these traits were ≤ 1.50. The highest rates of the pregnancy rate, lambing rate, and fecundity and gestation productivity were 75.9%, 70.9%, 1.11 and 3.34 kg, respectively.

Effect of body condition score on dynamics of hemogram in periparturient Holstein cows

The aim of the present study was to show the effect of body condition score (BCS) on dynamics of hemogram in periparturition Holstein cows in a dairy environment. Sixty-seven Holstein cows from a commercial dairy farm were allocated in three—under, moderate, and over condition—groups. They were sampled and were hematologically analyzed every 10 days from 30 days to calving until 30 days postpartum. Values were compared among groups and within each group by one-way and repeated measure ANOVA, respectively. Correlation of BCS and parameters were measured by Pearson’s method. Hematocrit, erythrocyte counts, and hemoglobin (Hb) values significantly declined after calving (P < 0.05). Mean corpuscular hemoglobin (MCH) showed higher values than normal reference values. Leukocyte and neutrophil counts were within normal limits but inclined at calving. Lymphocyte counts declined at calving. Total plasma solids were within normal values, except on calving days, which the values declined. Fibrinogen values were within normal limits throughout, with a tendency to increase in postpartum period in moderate and over condition cows. BCS values showed significant correlations with hematocrit (r pre = 0.318, r post = 0.357), Hb (r pre = 0.276, r post = 0.295), MCV (r pre = 0.371, r post = 0.304), MCH (r pre = 0.355, r post = 0.184), leukocyte (r post = −0.148), lymphocyte (r post = −0.160), and fibrinogen (r pre = −0.175) (P < 0.05). A trend to a normocytic normochromic anemia was seen after calving, contributed to possible metabolic impairments and nutritional deficiencies. Leukocyte alterations on calving day showed the stress leukon pattern. Higher BCS values showed a positive effect on erythron and negative influence on leukon and vice versa.

Comparison of surgical variables and short-term postoperative complications in healthy dogs undergoing ovariohysterectomy or ovariectomy

To determine whether ovariohysterectomy (OVH) required more time to complete and was associated with more short-term postoperative complications than ovariectomy (OVE) in dogs. Randomized prospective clinical trial. 40 healthy, sexually intact female dogs. OVH (in 20 dogs) or OVE (20 dogs) was performed by use of standardized anesthetic and surgical protocols. Physical characteristics of the dogs, surgical variables, pain scores derived from behavior-based composite pain scales, and surgical wound characteristics were analyzed. Body weight, age, body condition score, and distance between the sternal manubrium and the pubic rim were comparable among dogs that underwent either surgical procedure. Body weight was positively correlated with the total duration of the procedure and with time required for closure of the surgical wound. No effect of body condition score was determined for any variable. Skin and fascia incision lengths relative to the distance from the sternal manubrium to pubic rim were significantly greater in dogs that underwent OVH, compared with those of dogs that underwent OVE, but total surgical time was not different for the 2 procedures. No other significant differences were detected between the 2 groups. Significant differences in total surgical time, pain scores, and wound scores were not observed between dogs that underwent OVH and dogs that underwent OVE via standardized protocols.

The effect of body condition score at calving and supplementation with Saccharomyces cerevisiae on milk production, metabolic status, and rumen fermentation of dairy cows in early lactation

The objective of this study was to examine the effects of live yeast (LY) supplementation and body condition score (BCS, 1–5 scale) at calving on milk production, metabolic status, and rumen physiology of postpartum (PP) dairy cows. Forty Holstein-Friesian dairy cows were randomly allocated to a 2 × 2 factorial design and blocked by yield, parity, BCS, and predicted calving date. Treatments were body condition at calving (low for BCS ≤3.5 or high for BCS ≥3.75; n=20) and supplementation with LY (2.5 and 10g of LY/d per cow for pre- and postcalving, respectively; control, no LY supplementation; n=20). The supplement contained 109 cfu of Saccharomyces cerevisiae/g (Yea-Sacc1026 TS, Alltech Inc., Nashville, TN). Daily milk yield, dry matter intake, milk composition, BCS, body weight, and backfat thickness were recorded. Blood samples were harvested for metabolite analysis on d 1, 5, 15, 25, and 35 PP. Liver samples were harvested by biopsy for triacylglycerol (TAG) and glycogen analysis on d 7 precalving, and on d 7 and 21 PP. Rumen fluid was sampled by rumenocentesis for all cows on d 7 and 21 PP. Supplementation with LY had no effect on milk yield, dry matter intake, rumen fluid pH, or blood metabolites concentration of dairy cows with high or low BCS at calving. Feeding LY increased rumen acetate proportion and protozoal population, tended to increase liver glycogen, and decreased rumen ammonia nitrogen during early lactation. Over-conditioned cows at calving had greater body reserve mobilization and milk production and lower feed intake, whereas cows with a moderate BCS at calving had greater feed intake, lower concentrations of nonesterified fatty acids and β-hydroxybutyrate, lower liver TAG and TAG:glycogen ratio, and faster recovery from body condition loss. Additionally, the data suggest that concentrations of liver enzymes in blood might be used as an indicator for liver TAG:glycogen ratio. Results indicate that in the case of this experiment, where the control treatment was associated with an acceptable rumen pH, feeding yeast did not significantly improve indicators of energy status in dairy cows.

Effect of body condition score of does and use of bucks subjected to added artificial light on estrus response of Alpine goats

The effects of body condition score of does and exposure to sexually active bucks after exposure to long-day artificial photoperiod were examined in mature anovulatory French Alpine goat in Northern Mexico. In June, goats in good (2.3 +/- 0.2, scale 1 to 4; n = 10) or poor (1.6 +/- 0.3; n = 10) body condition were exposed during 15 day to sexually active bucks, which had been exposed to long photoperiod (16:8-h light-dark cycle, starting in December). A third group of goats in good body condition was exposed to bucks kept under the natural photoperiod of this region (26 degrees N). All goats in good body condition exposed to bucks treated with prolonged photoperiod exhibited estrus behavior, whereas only 50% of the does in poor body condition showed estrous behavior during the 15-day buck exposure. None of the does in good body condition showed estrus when exposed to bucks under natural photoperiod. These results revealed that a good body condition is required for maximum estrus response in anestrous Alpine goats and that exposure of bucks to long photoperiod in winter is essential for an adequate stimulus to reestablish estrus cycles in anovulatory Alpine does in Northern Mexico.

Effect of Body Condition Score on Productive Performance of Local Karadi Cows

Twenty one Karadi cows raised at Bakrajo Farm, College of Agriculture, University of Sulaimani,&#x0D; Kurdistan Region, Iraq, over the period April 2006 – May 2007 were used in this study. Cows were&#x0D; naturally mated, then calved between 13th of June 2006 and 21st of January 2007. Cows were scored&#x0D; according to the East of Scotland College of Agriculture system (ESCA) for their body condition at two&#x0D; periods; sixty days before the expected calving, and at calving (1-3 days after calving). Data were&#x0D; analyzed using the General Linear Model (GLM) procedure system by Statistical Analysis System (SAS).&#x0D; The overall means of milk yield of 8 weeks, total milk yield, peak milk yield, persistency, and&#x0D; lactation period were 217.76 ± 18.13 kg, 290.43 ± 34.10 kg, 35.00 ± 2.69 kg/week, 4.29 ± 0.28 week, and&#x0D; 89.38 ± 7.01 days, respectively. Body condition score at drying off and at calving had a significant effect&#x0D; on 8 weeks, total milk yield, peak milk yield and persistency. Lactation period was affected by body&#x0D; condition score at drying off, whereas body condition score at calving not affected the former trait.&#x0D; Parity and season of calving not affected the former traits.

Effect of Body Condition and Supplementary Feeding on the Reproductive Performance of Awassi Ewes

This study was conducted to evaluate the effect of body condition score (BCS) and supplementary feedingon the reproductive performance of Awassi ewes.One hundred sixty Awassi ewes aged 3-5 years (Average live weight 47.41±0.76) were used in acompletely randomized design. Six weeks before mating ewes were screened for their body conditionscore (BCS) and divided into two groups, low BCS (&lt;2.0) and high BCS (&gt;2.0) and ewes in each groupwere subdivided according to BCS and to non-supplemented and supplemented groups (n=40 ewes).Therefore, the four groups were:1. Group (LBCN) = Low Body Condition Non-supplemented.2. Group (LBCS) = Low Body Condition Supplemented.3. Group (HBCN) = High Body Condition Non-supplemented.4. Group (HBCS) = High Body Condition Supplemented.All ewes received ad libitum barley straw, and (350g DM/ewe/day) whole barley grains. The supplementedgroups (groups 2 and 4) were fed Mating Feed Blocks (MFB) ad libitum. Mature fertile Awassi rams(Three rams / group) were run with each group.The results showed that the pre-mating, mating, andpost-mating condition scores and body weights of the non-supplemented Ewes (Groups 1 and 3) aremaintained throughout the trial. Ewes offered supplementary feed the supplemented ewes (Groups 2and 4) gained in body condition score and weights, the differences were not significant. The BCS andweights at mating for supplemented groups are 2.12, 2.64 and 46.11, 53.38 kg for groups 2 and 4respectively. The results showed that the reproductive performance of Awassi ewes improved considerablydue initial BCS and MFB supplementation. The percent of ewes lambed after mating during the first andsecond estrus cycles were significantly (P&lt;0.05) affected by ewes' initial BCS and MFB supplementation.The percent of ewes lambed in first cycle were 50%, 77%, 72.3% and 87% for groups LBCN, LBCS,HBCN and HBCS respectively. Supplementation of low BCS ewes resulted a significant (P&lt;0.05)improvement in conception rate (17.5%) and lambing rate (12%). The results have not shown anysignificant of initial BCS and supplementation on twinning percentage. The percent of barren ewes at endof the trial was higher (20%, P&lt;0.05) in LBCN compared

Effect of Body Condition Score on Performance Traits in Crossbred Dairy Cows

Singh, R.R., Dutt, T., Joshi, H.C., Sinha, R.R.K. and Singh, M. 2009. Effect of body condition score on performance traits in crossbred dairy cows. J. Appl. Anim. Res., 36: 283–286. Sixty crossbred cows from three different genetic groups (1/2 Holstein Friesian (F) × 1/2 Hariana (H), 1/2F x1/4 Brown Swiss × 1/4 H), (1/2Fx1/4 Jersey × 1/4 H) were randomly selected to study body condition score after calving and its association with performance traits. The correlations between body condition score and body weight at different stages of lactation were positively significant. The correlations between body condition score and peak yield were negative and significant at 42nd (-0.316) and 56th (-0.404) day of lactation. The effect of body condition score on other performance traits was found to be non- significant. It is concluded that high producing cows mobilize greater amount of body condition score than the low producing cows in early lactation.

Effect of Body Condition Score of the Dairy Cow on the in vitro Immune Response of Peripheral Blood Mononuclear Cells to Progesterone Stimulation

Immune function in cows is closely associated with their physical and hormonal conditions. In order to clarify the relationship between the body condition score (BCS) of lactating dairy cows and the immune response to progesterone (P(4)) in vitro, we examined whether lower BCS in dairy cows affects the responsiveness of peripheral blood mononuclear cells (PBMCs) to P(4) added in to culture medium. Forty-two non-pregnant healthy Holstein dairy cows were examined at 61 to 120 days after calving. The cows were divided into the following two groups; Low BCS group (N=20), which had a BCS of less than 2.25, and a Control group (N=22), which had a BCS over 2.75. PBMCs were stimulated with P(4) (1 microg/mL) and/or phytohemagglutinin (PHA), and the levels of cytokine mRNA were analyzed. In the Low BCS group, a significantly lower IFN-gamma level was stimulated by PHA only compared with the Control group. The combination of P(4) and PHA significant decreased the IFN-gamma/IL-4 ratio in the Control group, but this reaction was not found in the Low BCS group. Our data indicated that expression of IFN-gamma mRNA was basically lower in the low BCS dairy cows and that addition of P(4) did not suppress the cellular immune function in these cows. In this study, we observed that P(4) reduced the cellular immune response in the adequate BCS cows, whereas immunosuppression by P(4) was not found in the PBMCs of the low BCS cows, which already had a lower level of immune function.

American Trypanosomiasis in Dogs from an Urban and Rural Area of Yucatan, Mexico

American trypanosomiasis in dogs is reported from South of the United States to Argentina and Chile. It is transmitted through the contact of dogs with reduviid insects when they feed; reduviid insects are well established in the southern state of Yucatan, Mexico. However, there are no reports available about trypanosomiasis prevalence in dogs of urban and rural areas. A cross-sectional study was performed in 345 stray dogs, 102 from a rural community of Yucatan (Tunkas) and 243 from Merida, capital city of the Yucatan state. Serum samples were obtained for detection of immunoglobulin G antibodies against Trypanosoma cruzi by indirect immunofluorescence assay and Western blot. DNA was extracted from whole blood of urban dogs for polymerase chain reaction (PCR) assay. Prevalence was determined and the risk to become infected in both urban and rural dogs was evaluated using a 2 x 2 contingency table. In addition to the effect of body condition score (BCS), the age and sex of dogs were also evaluated to determine the risk of infection. Antibody prevalence against T. cruzi in rural areas was 9.8%, whereas in urban dogs was 14.4%. When PCR results were included, prevalence in dogs from the urban area increased to 17.3%. PCR allowed the detection of active asymptomatic acute-phase disease. The risk to become infected was not different between urban and rural areas, suggesting that the vector is well adapted both to rural areas and urban sprawling. Dogs with poor BCS tended to have a higher probability of seroreactivity to T. cruzi proteins than dogs with regular or good BCS (p = 0.05).

Efeito da condição corporal ao parto sobre o desempenho produtivo de vacas mestiças Holandês × Zebu

Vinte e cinco vacas mestiças Holandês × Zebu foram utilizadas para avaliar o efeito da condição corporal ao parto sobre a produção e composição do leite e a mobilização de reservas corporais, avaliada por meio da variação da condição corporal do parto até os 120 dias de lactação. Os animais foram divididos em duas classes, de acordo com seu escore de condição corporal ao parto (ECCP), em uma escala de 1 (muito magra) a 5 (muito gorda): classe 1, vacas com ECCP &gt; 3,25; e classe 2, vacas com ECCP &lt;3,25. As classes diferiram entre si quanto ao escore de condição corporal ao parto; as médias foram de 3,71 e 2,58, respectivamente, para as vacas das classes 1 e 2. As vacas da classe 1 apresentaram maior mudança de escore de condição corporal (MECC) do parto aos 120 dias de lactação em relação às vacas da classe 2, com valores médios de -0,57 e -0,12 unidades de escore de condição corporal para os grupos 1 e 2, respectivamente. O escore de condição corporal ao parto não influenciou a produção de leite entre as classes 1 e 2, no entanto, influenciou a produção de leite corrigida para 3,5% de gordura, a porcentagem e a produção de gordura no leite. As vacas mestiças Holandês × Zebu apresentaram maior produção de gordura do leite e produção de leite corrigida para 3,5% de gordura quando escore de condição corporal ao parto foi maior que 3,0.

Effect of polymorphisms linked to LEP gene on its expression on adipose tissues in beef cattle

In cattle, genetic markers at the leptin (LEP) gene and at those linked to the gene have been described as affecting calving interval (markers LEPSau3AI and IDVGA51), or daily weight gain (BMS1074 and BM1500). This work investigated the effect of these alleles on LEP mRNA levels in cattle subcutaneous and omental adipose tissues. A sample of 137 females of a Brangus-Ibage beef cattle herd was analysed to evaluate the distribution of the polymorphisms; then, animals having at least one of the IDVGA51*181 (allele 181 at marker IDVGA51; six animals), LEPSau3AI*2 (four), BMS1074*151 (13), BM1500*135 (six) alleles and a control group composed of animals without any of these alleles (four animals) were submitted to surgery to obtain omental and subcutaneous adipose tissues. Leptin mRNA expression was quantified by TaqMan RT-PCR, using 18S rRNA as internal control and adjusted for the effect of body condition score, through regression analysis. Omental fat had LEP gene expression 33% lower than the subcutaneous tissue. Carriers of IDVGA*181 and BMS1074*151 showed subcutaneous fat leptin mRNA levels higher than the controls. Leptin controls feed intake and coordinates reproduction; therefore, animals with higher LEP gene expression will probably have lower daily weight gain than others with similar forage offer and nutritional condition and probably will also have longer calving interval.

Effect of body condition score at calving and diet energy content post calving on the fertility of dairy cows during early and mid-lactation

Poor reproductive performance is a major problem when considering the sustainability of the modern high yielding dairy cow, with reproductive costs being estimated at £500 million per annum across UK dairy herds (Lamming et al., 1998). Armstrong et al., (2001) stated that poor nutrition causes delayed puberty, aberrant oestrous cycles, lowered conception rates and reduced calf birth weight. Excessive and prolonged negative energy balance (NEB) has, on numerous occasions, been suggested as a major contributor to poor fertility and subsequent increased culling rates. In the present study the effects of a range of dietary treatments on energy balance and reproductive performance were evaluated.

The effect of body condition score on blood metabolites and hormonal profiles in ewes

The study was designed to investigate the effect of body condition score (BCS) on blood metabolites and hormones in order to assess the nutritional status and to identify which of those metabolites could be used as indicators for determining the nutritional status in ewes. Blood sampling and nitrogen balances were performed in four groups of five mature, dry and non-pregnant ewes with a different BCS namely: 1.25, 2, 3 or 4. Serum concentrations of insulin, non-esterified fatty acids, β-hydroxybutyrate, triglycerides, total lipids, albumin, globulins, total protein, urea, creatinine, insulin-like growth factor-I, and plasma glucose, glucagon, triiodothyronine, and thyroxine concentrations were determined. Results demonstrate a variation in metabolic status at the different BCSs. Undernutrition was more evident in the animals with a BCS of 1.25 but also in those with a BCS of 2. Ewes recorded lower plasma glucose, triiodothyronine and thyroxine concentrations and serum insulin, albumin, globulins, and insulin-like growth factor-I and higher serum non-esterified fatty acids, urea and creatinine. Overnutrition was obvious in ewes with a BCS of 4, reflected by high insulin, glucagon and urea levels. The BCS of 3 represented a more balanced metabolic status, as reflected by intermediate plasma glucose and glucagon, and serum insulin, albumin and globulins concentrations, and low values of urea and creatinine. The stabilization of body weight and BCS at 1.25, 2, 3 and 4 occurred at nutritional levels corresponding to 30, 60, 100 and 120% of the theoretical energy requirements for maintenance. This metabolic characterization clearly demonstrated that the BCS of ewes has a significant effect on metabolites and hormonal profiles. Ewes deal successfully with extreme nutritional conditions although a BCS of 3 appear to be ideal to assure nutritional and metabolic welfare and with a BCS below 2 or above 3 ewes seem more susceptibility to metabolic imbalances. From the variables tested as metabolic indicators glucose, non-esterified fatty acids and insulin provided the more reliable information for the diagnosis of the ewe's energy status and albumin and urea of the protein status.

CO-Synch enhances time to ovulation, cyclicity and pregnancy in anovulatory lactating Bos taurus/ Bos indicus cows

Induction of ovulation for timed artificial insemination (TAI) was evaluated in postpartum anovulatory and lactating Bos taurus/ Bos indicus cows ( n = 50). Palpation per rectum and transrectal ultrasonography were used on days − 30, − 20, − 10 and 0 (day 0 = start of treatment) to confirm the anovulatory status but with ovarian follicles ≥ 10 mm on day 0, and on the days of PGF 2α injection and pregnancy diagnosis to determine rates of ovulation and induction of cyclicity. Cows were randomly assigned to: (1) CO-Synch ( n = 25; day 0, 200 μg GnRH; day 7, 150 μg PGF 2α; day 9, 200 μg GnRH + TAI) and (2) control ( n = 25; no treatment). Rates of ovulation for the first GnRH injection, pregnancy and cyclicity induction were greater for CO-Synch ( P < 0.05). There was no effect of body condition score (BCS) ( P > 0.05). In conclusion, the CO-Synch protocol resulted in acceptable rates of cyclicity induction and pregnancy to TAI in anovulatory and lactating B. taurus/ B. indicus cows under tropical conditions.

Lipogenic activity in Rasa Aragonesa ewes of different body condition score

The aim of the study was to assess the effect of body condition score on tissue and metabolic characteristics of the adipose depots in sheep of Rasa Aragonesa breed. Ewes were uniformly assigned according to their body condition score (BCS) (scale 0 to 5), to four groups: 0.75–1.75, 2–2.75, 3–3.75, and 4–4.5. The amount of fat and the adipocyte size in the different adipose depots increased as BCS did (P &lt; 0.001) while the number of adipocytes did not change. The greatest ability to accumulate or mobilize fat was the subcutaneous depot (slope of the regression between amount of fat and BCS, b = 1.92; P &lt; 0.001). Fatty acid synthase (FAS) lipogenic enzyme activity was affected by BCS, while G3-PDH and G6-PDH activities were not. Key words: Adipose tissue, body condition score, adipocyte size, lipogenic enzyme activity, ewes

Induction of ovulation with GnRH and PGF2a in lactating Bos taurus × Bos indicus cows

Induction of ovulation for timed artificial insemination (TAI) with the Ovsynch protocol was evaluated in 49 anoestrous and lactating Bos taurus x Bos indicus cows. Palpation per rectum and transrectal ultrasonography were used on Days -30, -20, -10 and 0 (start of treatment) to confirm anoestrus but with the presence of follicles > or = 10 mm, and every other day during treatment to determine ovarian activity. Cows were randomly assigned to: (1) Ovsynch (n = 24; Day 0, 200 microg GnRH; Day 7, 150 microg PGF2alpha; Day 9, 200 microg GnRH + TAI 16 to 20 h later) and (2) control (n = 25; no treatment). Rates of ovulation for the first GnRH injection, detection of a corpus luteum (CL) at PGF2alpha injection, pregnancy and induction of cyclicity were greater (P < 0.05) with Ovsynch. There was no effect of body condition score (P > 0.05). In conclusion, the Ovsynch protocol was not effective in obtaining acceptable pregnancy rate for TAI, but it was effective for induction of cyclicity in anoestrous and lactating Bos taurus x Bos indicus cows under tropical conditions.

Effect of Body Condition at Calving and its Changes During Early Lactation on Postpartum Reproductive Performance of Zebu Cows in a Tropical Environment

Delgado, R., Magaña, J.G., Galina, C. and Segura, J.C. 2004. Effect of body condition at calving and its changes during early lactation on postpartum reproductive performance of Zebu cows in a tropical environment. J. Appl. Anim. Res., 26: 23–28. A herd was monitored for two years in order to determine the effect of body condition score on the reproductive performance of Zebu cows managed under continuous mating in the tropics of Mexico. Overall cyclicity and pregnancy rates were 60.5% and 37.1% at four months pospartum, respectively. 62.9 percent of the cows were non-pregnant and of these more than 60% were in true anoestrus. Body condition score (BCS) at calving and 60 days postpartum, BCS changes, season and parity had significant effects (P<0.05) on cyclicity and pregnancy at 120 days postpartum. The odds of a cycling or pregnant cow at 120 days postpartum improved with increasing BCS grades. Cows calving in the dry or rainy season had lower odds (0.5 and 0.7, respectively) than those calving during the windy and rainy season. First calving cows had the worst performance, no differences being observed among multiparous cows.