Identification of Fertility Rates in Swamp Buffalo Heifers Through Reproductive Tract Score and Cervical Mucus Analysis

The fast growth of buffalo (Bubalus bubalis) herds has placed this livestock species as a suitable alternative for animal protein production in the Venezuelan tropics. As with any domestic species with food production interest, the buffalo’s reproductive performance has a paramount relevance, which may be improved by applying the technique of reproductive tract scores (RTS). Using rectal palpation, the RTS (scale 1-5) assign the following scores: 1=flabby uterus and ovaries both <10 mm of diameter with no detectable follicles; 2=flabby uterus and ovaries both 10-15mm of diameter with <8 mm follicles; 3=soft tone uterus and ovaries both <15-20 mm of diameter with 8-10 mm follicles; 4=good tone uterus with 20-25 mm of diameter, ovaries >20mm with >10 mm follicles; 5= good tone uterus >25 mm of diameter, ovaries >20mm with evident luteal tissue. Therefore, the objective of this study was to validate the technique of RTS in pre-service buffalo heifers as a management strategy to improve the pregnancy rate. One-hundred and ten buffalo heifers with ages of 27 + 3 months and body weight of 354,32 + 24,14 kg were assessed for RTS before starting a breeding season of 120 days (Sep-Dec 2020) with four buffalo bulls in a proportion male to female 1:30. 67% of buffalo heifers were found with RTS among 3-5 (mature tract), while 33% were found with RTS among 1-2 (immature tract). Pregnancy was diagnosed 60 days after the end of the breeding season. Data was analyzed by Logistic Regression. A linear and positive increase association (p<0.02) was observed between RTS and pregnancy rate (RTS=5:85%, RTS=4:80%, RTS=3:74%, RTS=2:62%, and RTS=1:50%) indicating a beneficial effect of reproductive tract maturity on pregnancy rate. Likewise, body weight at service and pregnancy rate were also associated (p<0.0001). It was concluded that RTS is a good predictor of pregnancy rate in buffalo heifers. Thus, applying RTS at a field level should be a beneficial management tool.

Reproductive tract scoring (RTS) systems have been effective in evaluating fertility of heifers. A similar RTS system has not been reported in lactating dairy cows pertaining to conception rates following artificial insemination. Objectives of this study include development of a RTS system for lactating dairy cows and determining if RTS had an effect on artificial insemination (AI) success with various types of semen [conventional (CS), sexed (SS)]. During pre-breeding examinations (typically 30–60 DIM) by trained personnel, cows were assigned a RTS (1, 2, or 3) based on size and length of the cervix and uterine horns, but not including status of the ovaries. Tracts for RTS 1 were small, compact uterine horns resting within the pelvic cavity, RTS 2 were intermediate in size with uterine horns resting partially outside the pelvic cavity, and RTS 3 were large, deep tracts resting entirely outside the pelvis into the abdominal cavity. Additionally, cows were evaluated for RTS at a local abattoir before harvest, and tracts collected for volume and length measurements. Volume measurements were collected using Foley catheters and measuring water displaced in the uterine horns at a constant pressure. Length of the vagina, cervix, and uterine horns were measured using a flexible tape. Insemination data analysis was performed using mixed model analysis of variance in Glimmix SAS 9.2 (SAS Institute Inc., Cary, NC, USA). Insemination data included 613, 308, and 572 scores in first, second, and third+ lactation cows, respectively. First-lactation cows had 65.25% with RTS 1, 30.02% RTS 2, and 4.73% RTS 3. Second-lactation cows had 53.25% RTS 1, 39.29% RTS 2, and 7.47% RTS 3. Cows with 3+ lactations had 43.18% RTS 1, 43.88% RTS 2, and 12.94% RTS 3. Cows were artificially inseminated (n = 2401 inseminations) with either CS (n = 1981) or SS (n = 420). Conception rates for CS were 38.65%, 34.26%, and 24.41% for RTS 1, 2, and 3, respectively (P = 0.0154 for RTS 1 v. 3). Conception rates for CS (38.65%, RTS 1; 34.26%, RTS 2) were higher compared to SS (21.37%, RTS 1 (P = 0.0001); 20.72%, RTS 2 (P = 0.0186)). No differences were detected between CS (24.40%) and SS (22.35%) within RTS 3; however, observations were limited for SS inseminations with RTS 3. Preliminary data regarding total length (vagina, cervix, and uterine horns; RTS 1, 2, 3 = 103.1 cm, 114.9 cm, 134 cm, respectively) and volume (RTS 1, 2, 3 = 102 mL, 131 mL, 133.3 mL, respectively) suggest both increase as RTS increases but limited observations prevent conclusions at this time. Conception rates indicate smaller reproductive tracts have improved fertility in lactating dairy cows when using CS. Identification of larger reproductive tracts will allow for more economically efficient AI programs by utilising inexpensive, high fertility semen.

Effect of reproductive tract scoring on reproductive efficiency in beef heifers bred by timed insemination and natural service versus only natural service

Studies on reproductive tract score (RTS) and antral follicle count (AFC) in Senepol cattle are limited. These traits are essential as they are linked to the reproductive ability and reproductive performance of animals. Understanding the heritability and genetic correlation of these traits is crucial for guiding selection programs and selecting animals with greater reproductive efficiency and higher production potential. Therefore, this study aimed to estimate the genetic parameters of weight, RTS, and AFC in Senepol cattle using transrectal ultrasonography. Reproductive data were collected from 850 female Senepol cattle aged 10-16 months. At the time of evaluation, the following were measured: RTS traits (scores from 1 to 5), AFC (0 to 100), and female weight (kg). Variance and covariance components, genetic heritability, and correlations were estimated by univariate and bivariate analyses using the bull model. Heritability estimates were moderate for AFC (0.52) and weight (0.46), and low for RTS (0.12). The genetic correlation between RTS and AFC was almost zero (-0.05). The estimated genetic correlation between weight and AFC was -0.41, while the correlation between weight and RTS was 0.48. Selective breeding of AFC and RTS can enhance the reproductive efficiency of the herd and result in animals with earlier pubertal age and increased fertility.

Estrous synchronization strategies to optimize beef heifer reproductive performance after reproductive tract scoring

This study investigated the potential improvement in reproductive efficiency through reproductive tract scoring (RTS) of heifers 30-60 days prior to breeding. Between 2000 and 2004, the RTS of 1986 heifers (mean age of 395 days) were determined in two locations in Georgia, USA as part of the Heifer Evaluation and Reproductive Development (HERD) project. These heifers were of similar age and were managed using comparable nutrition and management protocols. The Kaplan-Meier product-limit method was used to analyse the number of days from the start of the breeding period to conception for heifers with different RTS classifications. RTS was significantly associated with both time to conception and the proportion of heifers that conceived during the breeding period. The mean time to conception for heifers in the combined RTS 1 and 2 category (37.8 days) was significantly longer than for heifers with scores of 4 (19.7 days) or 5 (15.8 days), but not significantly different from heifers with RTS of 3 (29.2 days). The estimated percentages of heifers that would have conceived during a uniform 70 day breeding period were 94.6% of RTS 5, 91.2% of RTS 4, 87.6% of RTS 3, and 70.5% of RTS 1 and 2. This study indicates that reproductive tract scoring can be used to assist producers in the selection of heifers that will conceive at a higher rate and breed earlier during the breeding season.

Studies on reproductive tract score (RTS) and antral follicle count (AFC) in Senepol cattle are limited. These traits are essential as they are linked to the reproductive ability and reproductive performance of animals. Understanding the heritability and genetic correlation of these traits is crucial for guiding selection programs and selecting animals with greater reproductive efficiency and higher production potential. Therefore, this study aimed to estimate the genetic parameters of weight, RTS, and AFC in Senepol cattle using transrectal ultrasonography. Reproductive data were collected from 850 female Senepol cattle aged 10-16 months. At the time of evaluation, the following were measured: RTS traits (scores from 1 to 5), AFC (0 to 100), and female weight (kg). Variance and covariance components, genetic heritability, and correlations were estimated by univariate and bivariate analyses using the bull model. Heritability estimates were moderate for AFC (0.52) and weight (0.46), and low for RTS (0.12). The genetic correlation between RTS and AFC was almost zero (-0.05). The estimated genetic correlation between weight and AFC was -0.41, while the correlation between weight and RTS was 0.48. Selective breeding of AFC and RTS can enhance the reproductive efficiency of the herd and result in animals with earlier pubertal age and increased fertility.

Previous studies have found an inverse correlation between anogenital distance (AGD) and beef and dairy cattle fertility, with greater fertility observed in females with short AGD. It has been previously demonstrated that heifers with mature reproductive tracts, as assessed by reproductive tract scores (RTS), have improved fertility to artificial insemination programs. The objective of this study was to explore the relationship between AGD, RTS, and conception rates to timed-artificial insemination (TAI) in Bos taurus commercial yearling beef heifers (n=884). All heifers were assigned to RTS on a scale from 1 to 5 at least two days before the beginning of the TAI protocol. Reproductive tract scores were determined based on uterine horn diameter and uterine tone, where 1=immature, <20mm diameter and no tone; 2=20-25mm diameter and no tone; 3=20-25mm diameter with slight tone; 4=30mm diameter with good tone; 5= >30mm diameter with good tone. Heifers from 8 different locations in the states of Kansas and Tennessee were utilized during the years of 2023 and 2024. All heifers were enrolled in a controlled internal drug release (CIDR)-based estrus synchronization protocol and received TAI. Pregnancy status was determined by transrectal ultrasonography approximately 45 days post TAI. The AGD was defined as the distance from the middle of the anus to the base of the clitoris, and was assessed using digital calipers at CIDR insertion, withdraw, TAI, or pregnancy diagnosis based on location. Results indicate a moderate correlation between RTS and AGD (r=0.32; P< 0.0001). Additionally, there was an effect of Location (P< 0.001) and RTS (P=0.003), but no effect of AGD (P=0.151) on conception rates to TAI, and there was no difference in average AGD between heifers that were diagnosed as pregnant or open to TAI (P= 0.1935; 83.2mm, and 84.2mm, respectively). We conclude that RTS is a more accurate assessment of beef heifer fertility to TAI than AGD.

Ultrasonographic reproductive tract measures and pelvis measures as predictors of pregnancy failure and anestrus in restricted bred beef heifers

BackgroundArtificial insemination is a preferred breeding method for beef heifers as it advances the genetic background, produces a predictive and profitable calving season, and extends the heifer’s reproductive life span. As reproductive efficiency in heifers is key for the success of beef cattle production systems, following artificial insemination, heifers are exposed to a bull for the remainder of the breeding season. Altogether, up to 95% of heifers might become pregnant in their first breeding season. Heifers that do not become pregnant at the end of the breeding season represent an irreparable economical loss. Additionally, heifers conceiving late in the breeding season to natural service, although acceptable, poses serious losses to producers. To minimize losses due to reproductive failure, different phenotypic parameters can be assessed and utilized as selection tools. Here, we tested the hypothesis that in a group of pre-selected heifers, records of weaning weight, age at weaning, age at artificial insemination, and age of dam differ among heifers of varied reproductive outcomes during the first breeding season.ResultsNone of the parameters tested presented predictive ability to discriminate the heifers based on the response variable (‘pregnant to artificial insemination’, ‘pregnant to natural service’, ‘not pregnant’). Heifers categorized with body condition score = 6 and reproductive tract score ≥ 4 had the greatest proportion of pregnancy to artificial insemination (49% and 44%, respectively). Furthermore, it was notable that heifers presenting body condition score = 6 and reproductive tract score = 5 presented the greatest pregnancy rate at end of the breeding season (89%). Heifers younger than 368 d at the start of the breeding season did not become pregnant to artificial insemination. Those young heifers had 12.5% chance to become pregnant in their first breeding season, compared to 87.5% if the heifers were older than 368 days.ConclusionOur results suggest that beef heifers with body condition score = 6 and reproductive tract score ≥ 4 are more likely to become pregnant to artificial insemination. Careful assessment should be undertaken when developing replacement heifers that will not reach 12 months of age by the beginning of the breeding season.

Growth and reproduction genomic-polygenic and polygenic parameters and prediction trends as Brahman fraction increases in an Angus-Brahman multibreed population

Nutritional management in replacements heifer is important to optimize the profitability of livestock farms. Food resources with high conversion rates offered in self-feeders achieve efficiency with easy management. It´s possible that the use of high-concentrate diets with the inclusion of additive to regulate intake contributes to increase animal performance and reproductive development in heifers. The aim of this work was to evaluate different rearing diet strategies with r-zeta® additive on replacements heifer performance and reproductive. One hundred twenty Hereford heifers (9,1± 1,7 month and 192,6 ± 19,0 kg body weight -BW-) were assigned to different treatments according to different diets to evaluate r-zeta® additive that regulate intake and modulate the ruminal microbiota. The defined treatments were HR+CS (hay roll and daily control supplementation at 1% BW); HR+Sr-zeta® (hay roll and daily balanced pellet r-zeta® supplementation at 1% BW); HR+SFr-zeta® (hay roll and self-feeding balanced pellet r-zeta®) and SFr-zeta® (self-feeding balanced pellet r-zeta®). In treatments with supplementation, ration was offered in linear feed bunks (daily supply) and in treatments with self-feeders was offered weekly. Triticale hay rolls were offered ad libitum. The control supplement and the balanced pellet were formulated with 36% PC/kg DM and 2.4 Mcal ME/kg DM. And the hay roll had 7.9% PC/kg DM and 1.3 Mcal ME/kg DM. The BW were used to adjust the supplement supply in the treatments HR+CS and HR+Sr-zeta®. Average daily gain (ADG), dry matter intake (DMI) and conversion (C) were estimated. Reproductive tract scoring (RTS) was measured at the final of the experience (day 83) and each heifer was scored from 1 (prepubertal) to 5 (cyclic). Data were performed using Infostat. The continuous variables studied were analyzed by ANOVA and RTS was compared by using a chi-square analysis. Significant differences were considered at p≤ 0.05. Heifers fed with r-zeta® in treatments with balanced pellet offered in self-feeders had higher ADG regarding those supplemented (1.2 vs. 0,7 kg/d). Total DMI (% LW) was lower in SFr-zeta® regardless to other treatments (2.4 vs. 2.6 to 2.8 % LW). In this sense, best conversion was in treatments with self-feeding balanced pellet with r-zeta® regardless of hay roll inclusion (Table 1). Finally, treatments with inclusion of the multifactorial additive had a higher proportion of heifers with good reproductive development (RTS 4 and 5). In the HR+CS, only 13% of the animals had this condition while in the HR+Sr-zeta®, HR+SFr-zeta® and SFr-zeta®, the 30, 39 and 37% were into RTS 4 and 5. In conclusion, r-zeta® additive in high-concentrate diets could be a strategy to use in raising heifers to improve their growth and reproductive development.

Fertility after implementation of long- and short-term progesterone-based ovulation synchronization protocols for fixed-time artificial insemination in beef heifers

Antral follicular count has limited impact in the selection of more fertile beef heifers

The research aimed to investigate the impact of reducing the time interval for progesterone exposure on the ovulatory follicle just before performing fixed-timed artificial insemination (FTAI). This was achieved by adjusting the timing of administering a gonadotropin-releasing hormone agonist (GnRH; specifically, 100 µg gonadorelin, known as Cystorelin). The study assessed the effectiveness of two estrous synchronization protocols, the “7 & 7 Synch” and a modified protocol, by examining estrus expression (EE) and the resulting pregnancy rates (PR) following FTAI. The research utilized frozen conventional Angus semen from Select Sires, Inc. (Plain City, OH), and involved 66 Angus-cross heifers from the beef cattle research unit near Fayetteville at the University of Arkansas. To ensure consistency, the heifers were divided into two treatment groups based on their cyclicity status (CYC) and age. CYC status was determined by assessing a reproductive tract score (RTS) 1 wk before the synchronization process. RTS scores ranged from 1 to 5, with RTS 1-3 indicating pre- or peripubertal status and scores of 4 and 5 indicating cycling. Heifers with an RTS of 1 and 2 were excluded from the study before synchronization commenced. Both treatment groups involved the insertion of a controlled internal drug-releasing device (CIDR; specifically, Eazi-breed, containing 1.38 g of progesterone) into the vagina on d -14. Simultaneously, a prostaglandin F2α analogue (PGF; 500 µg cloprostenol sodium, known as Synchsure) was administered. In the first treatment group (7&7), GnRH was administered on d -7, while in the second group (8&6), GnRH was given on d -6. In both cases, PGF was administered on d 0 when the CIDR was removed, precisely 72 ± 1 h before FTAI, along with another dose of GnRH. Estrus expression (EE) was assessed during FTAI by examining Estrotect patches (Rockway Inc., Spring Valley, WI). EE was considered present when a patch had 50% or more of its color rubbed off, and it was deemed absent when less than 50% of the color had worn off. Pregnancy rates (PR) were determined through ultrasound examination on d 55. EE and PR were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC). Statistical differences were declared at α ≤ 0.05 and tendencies declared between 0.05 < P ≤ 0.1. Heifers on the 8&6-d protocol had greater rectal temperatures at breeding compared with 7&7-d heifers (P < 0.0001). AI pregnancy rates were greater in heifers on the 8&6-d protocol compared with the heifers on 7&7-d protocol (P = 0.625) with average pregnancy rates of 39.4% and 30.3%, respectively. Overall, pregnancy rate was greater as well for the 8&6-d heifers compared with the 7&7-d heifers (P = 0.044), with mean overall pregnancy rates of 78.8% and 54.5%, respectively.