Effect of galectin-1 administration on pregnancy rate and its economic viability in TAI procedures in beef cattle

The purpose of this work is to demonstrate the reproductive efficacy and the economic impact of a complementary tool to the TAI (timed artificial insemination) protocols - the administration of a single dose of recombinant human galectin-1 (rHGAL1) during the insemination procedure. GAL-1 can be considered as a modulator of the pregnancy development process. Reproductive efficacy was verified through the pregnancy rate in the first service, by ultrasonography (at 28-35 days) in contemporary groups (YG) of cows subdivided into 02 experimental groups (Control Group, composed of cows inseminated in a conventional and Treated group, composed of cows inseminated with rHGAL-1 administration following the deposition of the semen dose). Ninety YG were formed, grouping cows under identical conditions (inseminator, farm/lot, breed, animal category, semen/bull variables). The experiment was conducted in 15 farms, with 3,125 cows (Nellore and crossbred), all multiparous and with calf at foot (from 60 to 100 days old) and who maintained a body score (BSC) between 3.5 and 2.5 in the act of the TAI protocol and in the pregnancy diagnosis. It was demonstrated, by the proposed statistical method, that the “rHGAl-1 dose” effect was significant, increasing the probability of obtaining pregnancy by 8.38 percentage points (p < 0.0001). Based on the construction of a hypothetical model, the economic profitability that can be obtained were compared. Using the average increase obtained by 8.38 percentage points more in the pregnancy rate, it was possible to increase productivity, adding, almost U$ 2 thousand to profitability for each 100 cows worked.

Influence of Days after Calving and Thermal Stress on the Efficacy of a Progesterone-Based Treatment in Acyclic Italian Mediterranean Buffalo

The aim of this study was to evaluate the efficacy of a progesterone-based treatment on anoestrus in buffaloes. Primiparous acyclic buffaloes (n = 276), were divided into three classes according to their days in milk (DIM): from 50 to 90 (Class I; n = 86), from 91 to 150 (Class II; n = 102) and from 150 to 200 (Class III; n = 88). Animals were synchronized using P4 vaginal implants, followed by timed artificial insemination (TAI). They were then allowed to enter into a larger group of buffaloes for natural mating 15 days after AI was performed, and pregnancy status was monitored from then on at 15-day intervals. Finally, the temperature–humidity index (THI) was calculated. Statistical analysis was performed by ANOVA by means and both multiple and linear regression. The total pregnancy rate (PR) was 87.7%, with no differences among DIM classes (88.0, 92.4, and 80.0% in Classes I, II, and III, respectively). However, the PR at TAI tended to be higher (p = 0.07) in buffaloes in Class II. The follicle (FL) area in Class II buffaloes was larger (p < 0.01) than that of the other classes. No influence of the THI on the total PR was recorded. The pregnancy outcome at TAI was affected by the FL area (odds ratio = 2.237; p < 0.05) and body condition score (BCS) (odds ratio = 1.256; p < 0.05). In conclusion, treatment with vaginal P4 optimizes pregnancy rates in anoestrus buffaloes, particularly when the animals are in mid-lactation and show an optimal BCS. Furthermore, the THI does not seem to affect the efficiency of the progesterone treatment.

PSVIII-16 Effect of estrous synchronization with natural service or fixed-timed artificial insemination with conventional or gender-skewed semen in beef females

Reproductive efficiency is critical for profitability, and age at weaning critically impacts weaning weight. The objective was to evaluate estrous synchronization and/or AI with conventional (CON) or gender-skewed (SEXED) semen on calving distribution. Beef females (n=1,620) were either 1) synchronized (7-CIDR:Syn) or not synchronized (Nonsyn) and mated to bulls, 2) synchronized (7-d CIDR) and mated to bulls (SynNS) or artificially inseminated (SynAI), or 3) synchronized (7-d CO-Synch plus CIDR) and AIed with CON or SEXED semen. Calving distribution and gender were determined at birth and were analyzed using the GLIMMIX procedure in SAS. Synchronization resulted in more calves born from d1 to 14 (P &lt; 0.01; 62% vs 47%) of the calving season. There was no differences (P = 0.31) between Syn and Nonsyn in the percent of calves born after d21, but between d22 and 42, more (P = 0.04) calves were born in the Nonsyn group. A greater proportion (P &lt; 0.02; 46% vs 38%) of calves were born in SynNS between d1 and 14 compared to SynAI. There was no difference between treatments (P &gt; 0.12) from d1 to 42, but more calves were born for SynAI after d43. With SEXED semen, there were no differences (P &gt; 0.14) between CON and SEXED for the proportion of calves born from d1 to 14 or d1 to 21; however, more of the desired gender were born in the SEXED group during d1 to 14 of the calving season (P &lt; 0.01; 84% vs 68%). More total calves were born from d22 to 42 in the SEXED group compared to the CON group (P &lt; 0.05; 49% vs 33%). In summary, synchronization increased the proportion of females that calved early in the calving season, and SEXED semen increased the proportion of the desired gender born early in the calving season.

PSXII-20 Ovarian dynamics and fertility in beef cows administered a 5-day or 6-day CO-Synch protocol for timed artificial insemination

The 5-day CO-Synch is an extensively used TAI protocol; however, it requires multiple administrations of prostaglandin F2α (PGF). The objective of the present study was to evaluate the effect of increasing progesterone (P4) device insertion from 5 to 6 days during a TAI protocol on ovarian dynamics and fertility in beef cows. Suckled beef cows (n = 867) at six locations were randomly assigned to either a 5-day or 6-day CO-Synch. Cows received an intravaginal P4 device (CIDR, Zoetis) and 100 µg of gonadorelin acetate (GnRH, Parnell) on d-9 (6-day) or d-8 (5-day). On d-3 CIDR’s were removed, an estrus detection patch applied (Estrotect, Rockway Inc.) and either one (6-day) or two (5-day) doses of PGF (500 µg of cloprostenol sodium, Estroplan, Parnell) was administered. On d0 (72 h after CIDR removal) all cows received 100 µg of GnRH, estrus expression was evaluated, and AI was performed. Pregnancy was determined by ultrasonography 34 days after TAI. Ovarian dynamics were evaluated in a subset of animals (n = 20) between d-3 and d7 to determine preovulatory follicle size, time of ovulation and corpus luteum (CL) size. Data were analyzed using generalized linear mixed models (SAS 9.4). Cows in the 6-day group tended (P = 0.09) to have a larger maximum follicle diameter (16.2±0.4mm) than cows in the 5-day group (15.0±0.6mm). In addition, CL volume on d7 was greater (P = 0.01) in the 6-day (4302±495mm3) than 5-day (2406±455mm3) group. There were, however, no differences (P = 0.15) in the interval between CIDR removal and ovulation. Cows assigned to the 6-day group had greater (P &lt; 0.05) estrus expression [56.1% (215/385) vs 41.5% (161/388)] and pregnancy rate [54.6% (236/438) vs 47.4% (207/435)] than cows in the 5-day group. In conclusion, extension of the period of P4 device insertion in a prolonged proestrus protocol increases preovulatory follicle size, estrous expression, and fertility to TAI.

Estrus expression and pregnancy rates in heifers primiparous and multiparous Nelore cows subjected to timed artificial insemination with strategic use of gonadotropin-releasing hormone

We evaluated the effects of nulliparous, primiparous, and multiparous conditions on the estrus and pregnancy rates in females that did not show estrus but were treated with gonadotropin-releasing hormone (GnRH) at the time of timed artificial insemination (TAI). Nelore females (n = 531) were allocated according to the following categories: nulliparous (n = 144), primiparous (n = 132), and multiparous (n = 255). The animals received a conventional TAI protocol, and estrus expression was identified by the absence of paint in the sacrococcygeal region on the day of TAI. Females that did not show estrus were treated with 10 μg of GnRH together with insemination. The rates of estrus and pregnancy were analyzed using a logistic regression model (P < 0.05). The estrus expression was lower (P = 0.006) in the primiparous (61.36%) group than in the nulliparous (76.39%) and multiparous (75.69%) groups. Similar pregnancy rates were observed in females that showed estrus (nulliparous 84.54%, primiparous 86.42%, and multiparous 80.31%; P = 0.39) and in females that did not show estrus and received GnRH (nulliparous 41.18%, primiparous 56.86%, and multiparous 58.06%; P = 0.24). The total pregnancy rates were also similar (P = 0.98) among the categories (nulliparous 74.3%, primiparous 75.0%, and multiparous 74.9%). The primiparous females had a lower rate of estrus, and the pregnancy rates were similar among the categories that received GnRH.

PSVIII-11 Agent-based simulation model to evaluate the economic performance of reproductive programs in beef cattle

The objective of this study was to create a stochastic, agent-based simulation model to compare the economic performance of reproductive strategies in beef cattle. The model was parameterized using data from a real herd and the scientific literature. The scenarios evaluated were: natural mating (NM) only (ONM); one timed artificial insemination (TAI) plus NM (1TAI+NM); two TAI plus NM, with 24, 32, and 40 days between TAI (2TAI/24+NM, 2TAI/32+NM, and 2TAI/40+NM, respectively); three TAI without NM, with 24, 32, and 40 days (3TAI/24, 3TAI/32, and 3TAI/40, respectively), and three TAI plus NM, with 24 and 32 days (3TAI/24+NM and 3TAI/32+NM, respectively). The initial female herd was 400 and remained constant. The bull population varies from 0 to 15, depending on the scenario. The outcomes for each scenario are assessed on 32 farms, using a 5000-day time horizon at one-day time intervals and an animal-by-animal basis. The 3TAI/24+NM scenario resulted in the highest incomes (US$ 96,479.2 ± 709.8), while ONM had the least value (US$ 79,753.4 ± 741.9). The total operating cost was highest for 3TAI/24+NM (US$ 101,720.6 ± 79.2) and lowest for ONM (US$ 90,898.6 ± 59.2). However, when the total operating cost was evaluated per kg of weaned calf, the highest and lowest costs were for ONM (US$ 2.8 ± 0.0/kg) and 2TAI/24+NM (US$ 2.17 ± 0.0/kg), respectively. The 2TAI/24+NM (US$ -4,651.3 ± 630.7) scenario presented the best net margin, while the lowest result was for 3TAI/40 (US$ -12,590.0 ± 746.3). Our model suggests that reproductive strategies that use TAI have better economic performance than those under ONM. However, when three TAI were performed with 40 days, the benefit was lower, and even for some analyzes, it was worse than the ONM. The 2TAI/24+NM scenario outperformed the others because of the contrast between its high income with moderate costs.

AVALIAÇÃO DO DESEMPENHO REPRODUTIVO DE VACAS NA REGIÃO DO PANTANAL SUL-MATO-GROSSENSE SUBMETIDAS A IATF Com Aplicação De GnRH

A Inseminação artificial em tempo fixo (IATF) está se difundindo no Brasil, pois contribui para o aumento da produtividade. O objetivo neste trabalho foi avaliar o uso do GnRH em protocolos de IATF de vacas criadas no pantanal Sul-mato-grossense. Participaram da pesquisa 531 vacas paridas da raça Nelore, que foram avaliadas de acordo com o escore de condição corporal (ECC), submetidas a três tipos de protocolos de IATF (lote 1, 2 e 3). Após 40 dias da inseminação artificial foi realizado diagnóstico de gestação. As matrizes que não receberam GnRH no lote 1 (estro aparente), lote 2 (estro parcial) e lote 3 (sem apresentação de estro) apresentaram, respectivamente 55,4%, 19,2% e 25,9% de prenhez, enquanto as que receberam o fármaco apresentaram 48,6%, 37,2% e 38,8%. Relacionado ao ECC, pode-se observar que a maior taxa de prenhez ocorreu em animais com ECC 3. Primíparas apresentaram melhor taxa de prenhez quando receberam GnRH independente do ECC. Concluiu-se que o uso de GnRH mostrou-se eficiente para melhoria da taxa de prenhez principalmente em primíparas, assim como nos animais que não apresentaram estro ou apresentaram estro parcial, e que matrizes com ECC 3 apresentaram melhores taxas de prenhez que vacas com escore inferior. Palavras-chave: bovino de corte; inseminação artificial em tempo fixo; produtividade; GnRH; Nelore. Evaluation of cow reproductive performance in the region of Mato Grosso do Sul swamp submitted to TAI with GnRH application ABSTRACT: The technique of timed artificial insemination (TAI) is spreading in Brazil, as it contributes to the increase of productivity. The objective of this work was to evaluate the use of GnRH in TAI protocols of cows raised in the swamp of Mato Grosso do Sul. 531 Nelore breed calved cows participate in the survey, which were evaluated according to the body condition score (BCS), and then performed three types of TAI protocols (batch 1, 2 and 3). After 40 days of the insemination, a pregnancy diagnosis was made. The matrices that did not receive GnRH in batch 1 (apparent oestrus), batch 2 (partial oestrus) and batch 3 (no oestrus presentation) presented respectively 55.4%, 19.2% and 25.9% of pregnancy, while those receiving the drug showed 48.6%, 37.2% and 38.8%. Related to BCS, it can be observed that the highest pregnancy rate occurred in animals with BCS 3. Primiparous had a better pregnancy rate when receiving GnRH regardless of BCS. It was concluded that the use of GnRH was efficient to improve the pregnancy rate mainly in primiparous as well as animals that showed no oestrus or partial oestrus, and matrices with BCS 3 had better pregnancy rates than cows with lower scores. Keywords: beef cattle; timed artificial insemination; productivity; GnRH; Nelore.