BackgroundInfertility is a longstanding limitation in livestock production with important economic impact for the cattle industry. Female reproductive traits are polygenic and lowly heritable in nature, thus selection for fertility is challenging. Beef cattle operations leverage estrous synchronization in combination with artificial insemination (AI) to breed heifers and benefit from an early and uniform calving season. A couple of weeks following AI, heifers are exposed to bulls for an opportunity to become pregnant by natural breeding (NB), but they may also not become pregnant during this time period. Focusing on beef heifers, in their first breeding season, we hypothesized that: a- at the time of AI, the transcriptome of peripheral white blood cells (PWBC) differs between heifers that become pregnant to AI and heifers that become pregnant late in the breeding season by NB or do not become pregnant during the breeding season; and b- the ratio of transcript abundance between genes in PWBC classifies heifers according to pregnancy by AI, NB, or failure to become pregnant.ResultsWe generated RNA-sequencing data from 23 heifers from two locations (A: six AI-pregnant and five NB-pregnant; and B: six AI-pregnant and six non-pregnant). After filtering out lowly expressed genes, we quantified transcript abundance for 12,538 genes. The comparison of gene expression levels between AI-pregnant and NB-pregnant heifers yielded 18 differentially expressed genes (DEGs) (ADAM20, ALDH5A1, ANG, BOLA-DQB, DMBT1, FCER1A, GSTM3, KIR3DL1, LOC107131247, LOC618633, LYZ, MNS1, P2RY12, PPP1R1B, SIGLEC14, TPPP, TTLL1, UGT8, eFDR≤0.02). The comparison of gene expression levels between AI-pregnant and non-pregnant heifers yielded six DEGs (ALAS2, CNKSR3, LOC522763, SAXO2, TAC3, TFF2, eFDR≤0.05). We calculated the ratio of expression levels between all gene pairs and assessed their potential to classify samples according to experimental groups. Considering all samples, relative expression from two gene pairs correctly classified 10 out of 12 AI-pregnant heifers (P = 0.0028) separately from the other 11 heifers (NB-pregnant, or non-pregnant).ConclusionThe transcriptome profile in PWBC, at the time of AI, is associated with the fertility potential of beef heifers. Transcript levels of specific genes may be further explored as potential classifiers, and thus selection tools, of heifer fertility.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4505-4) contains supplementary material, which is available to authorized users.
Infertility is a challenging phenomenon in cattle that reduces the sustainability of beef production worldwide. Here, we tested the hypothesis that gene expression profiles of protein-coding genes expressed in peripheral white blood cells (PWBCs), and circulating micro RNAs in plasma, are associated with female fertility, measured by pregnancy outcome. We drew blood samples from 17 heifers on the day of artificial insemination and analyzed transcript abundance for 10,496 genes in PWBCs and 290 circulating micro RNAs. The females were later classified as pregnant to artificial insemination, pregnant to natural breeding or not pregnant. We identified 1860 genes producing significant differential coexpression (eFDR < 0.002) based on pregnancy outcome. Additionally, 237 micro RNAs and 2274 genes in PWBCs presented differential coexpression based on pregnancy outcome. Furthermore, using a machine learning prediction algorithm we detected a subset of genes whose abundance could be used for blind categorization of pregnancy outcome. Our results provide strong evidence that transcript abundance in circulating white blood cells is associated with fertility in heifers.
Background Artificial 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. Results None 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. Conclusion Our 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. Electronic supplementary material The online version of this article (10.1186/s40104-019-0329-6) contains supplementary material, which is available to authorized users.
16Infertility is a disease that affects humans and cattle in similar ways. The resemblance includes 17 complex genetic architecture, multiple etiology, low heritability of fertility related traits in females, 18 and the frequency in the female population. Here, we used cattle as a biomedical model to test 19 the hypothesis that gene expression profiles of protein-coding genes expressed in peripheral 20 white blood cells (PWBCs), and circulating micro RNAs in plasma, are associated with female 21 fertility, measured by pregnancy outcome. We drew blood samples from 17 female calves on the 22 day of artificial insemination and analyzed transcript abundance for 10496 genes in PWBCs and 23 290 circulating micro RNAs. The females were later classified as pregnant to artificial 24 insemination, pregnant to natural breeding or not pregnant. We identified 1860 genes producing 25 significant differential coexpression (eFDR<0.002) based on pregnancy outcome. Additionally, 26 237 micro RNAs and 2274 genes in PWBCs presented differential coexpression based on 27 pregnancy outcome. Furthermore, using a machine learning prediction algorithm we detected a 28 subset of genes whose abundance could be used for blind categorization of pregnancy outcome. 29Our results provide strong evidence that bloodborne transcript abundance is highly associated 30 with fertility in females. 42dissecting female fertility traits 20,21 . 43Beyond the importance as a biomedical model, cattle production systems provide 44 approximately 28% 22 of the protein supply globally. Improving cattle production efficiency is 45 essential for farmers to attain sustainable production and support the growing demand for animal 46 protein 22 . Infertility is a major factor that hinders efficiency in cattle production, and it starts with 47 limited success of pregnancy in young female calves. First breeding success greatly influences 48 the lifetime efficiency of beef replacement heifers. Heifers that calve early in their first calving 49 season experience increased productivity and longevity than their later calving herd 50 mates 23,24,25,26 . Furthermore, the genetic correlation between yearling pregnancy rate and lifetime 51 pregnancy rate is high (0.92-0.97) 27,28 . Therefore, the ability to identify heifers that experience 52 optimal fertility during the first breeding is essential to the sustainability of beef cattle production 53 systems. 54The examination of the genetic components of fertility in beef heifers have yielded several 55 genes potentially associated with fertility traits 5,6,7,8,9,10,11,12 , but the effect of these markers are 56 minimal, and there is no clear redundancy in genetic markers identified across breeds. Beyond 57 the genomic profiling, the analysis of multiple layers of an individual's molecular blueprint is likely 58 key for understanding the underlying biology of complex traits 29 . In line with this rationale, 59 expression-trait association studies have emerged as a means to better understand complex 60 traits 30,31 . Specificall...
Weaning is one of the most critical and stressful stages of a beef calf’s life. Management strategies practiced during the post-weaning period can have a large impact on calf performance, quality, and economic viability. With the number of different practices that producers can utilize during these stages of production, it is important for Extension educators to understand which management strategies are most commonly used and the potential successes of those practices. In spring 2022, an online survey was conducted to examine beef calf weaning and backgrounding management practices used by Alabama cattle producers. The survey was distributed through Qualtrics software and contained 24 total questions. There were 214 responses received by the end of the survey deadline. A total of 94% of respondents considered their operation to be a cow-calf operation with 52% of respondents identifying as a commercial cow-calf operation. Most participants (46%) indicated they had a smaller size herd of 50 head or less. Almost one-half of respondents (47%) had a calving season in the fall, 23% had a winter calving season, and 19% had a spring calving season. There was an 11% response of producers not having a defined calving season. Participants were asked to describe their method of calf weaning and of the methods listed, 55% said they abruptly wean and 38% reported that they utilize fenceline weaning. Over one-half (61%) of producers indicated that they background or precondition their calves and another 25% stated that they do in some years, but not always. For respondents that do not background, market unpredictability is the main concern when choosing to not precondition calves. Producers who responded that they do background calves indicated that they wean for at least 60 days before sale. These respondents also followed other important management strategies such as a vaccination program (83%), castration (81%) and use of implants (37%). Methods for marketing backgrounded calves differed across respondents with 49% of survey respondents using local livestock auctions as one method of selling their calves and 13% of producers retaining ownership of their calves through the feedyard finishing phase. With these data, potential educational gaps for cow-calf operations, such as marketing knowledge and opportunities have been identified. Extension educators in Alabama will be able to use these data to create resources and programs centered around backgrounding cattle to improve overall understanding related to calf management post-weaning.
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