Artificial Insemination Sires Research Articles

Differences in the choice of beef artificial insemination sires used by dairy producers versus beef producers

The growing demand among dairy producers for suitable beef sires to mate to their females creates the possibility of separate breeding programs to generate beef sires for the dairy sector versus those for the beef sector. Informing such a decision is the extent of the genetic differences among beef sires used by dairy producers relative to those used by beef producers. The objective therefore of the present study was to use a large national database of artificial insemination (AI) records in dairy and beef cow herds to establish the difference in mean genetic merit of beef AI sires used by dairy producers versus those used by cow-calf beef producers. The traits explored were gestation length, calving difficulty, and perinatal mortality as well as the 3 carcass traits of carcass weight, conformation, and fat score. Carcass conformation and fat score are mechanically assessed on a scale of 1 (poor conformation and low fat cover) to 15 (excellent conformation and high fat cover). Sire genetic merit differences for feed intake and docility were also examined. Estimates of genetic merit for all 8 traits on individual AI sires available at the time of service were used. A total of 1,230,622 AI records comprised 909,719 services from dairy herds and 320,903 services from beef herds were used. Of the 1,802 beef AI sires represented in the entire dataset, over half were used by both dairy and beef herds representing ≥98% of the services in each production system. However, the usage rate of individual AI sires differed between dairy and beef herds with the Spearman rank correlation between the quantity of inseminations per sire in dairy and beef herds being just 0.38. This correlation means that beef AI sires used heavily in the beef herd were not always those heavily used in dairy herds. A clear difference in the mean genetic merit of beef AI sires selected by dairy producers relative to those selected by beef cow-calf producers was obvious with the extent of the difference being a function of whether the female served was a nulliparous heifer or a cow. Much of the differences in genetic merit of chosen beef AI sires between dairy and beef producers was actually attributable to differences in breed choice, albeit some within-breed selection was also evident. Irrespective, dairy producers, on average, chose shorter gestation length sires whose progeny were genetically less predisposed to require intervention during the birthing process; these sires had genetic merit estimates expected to result in lighter and less conformed progeny carcasses relative to the beef AI sires used by beef producers. Results point to large differences in genetic merit of the beef AI sires chosen by dairy versus beef producers, much of which actually reflected differences in breed choice among dairy and beef producers.

PSIV-7 Multi-Sire Artificial Insemination of Beef Heifers in the Nebraska Sandhills May Increase Pregnancy Rate Compared with Single-Sire Insemination

Abstract The objective of these studies was to observe pregnancy outcomes resulting from artificial insemination (AI) with multi-sire semen (MS) compared with single-sire semen (SS) in beef heifers. One study compared MS AI to SS AI and the other study observed the pregnancy rate to AI using sexed MS semen. In the first study, three bulls were selected for AI of 441 heifers in year one. Heifers were synchronized with the melengestrol acetate – PGF2α – GnRH protocol using estrus detection and timed AI. Seventy-five single-sire straws of semen, from each bull, were labeled A, B, or C. Remaining semen was pooled together to form multi-sire semen straws. Heifers were artificially inseminated using alternating treatment of MS or SS; A, B, or C. Ultrasound determined pregnancy rate of heifers by treatment averaged 63% ± 5.5% (SS-A), 64% ± 5.5% (SS-B), 65% ± 5.5% (SS-C), and 69% ± 3.3% (MS). Heifers administered MS averaged 4.5% ± 4.5% greater than SS (P = 0.32) and 5.9% ± 6.4% greater than the least performing sire (P = 0.36). The observed differences between MS and SS pregnancy rate are less than previous research suggests. It is hypothesized the best fertilization period for a sire and dam may differ between individuals and herds leading to variability in pregnancy rates. In the second study, multiple unproven bulls were selected for AI of 868 ± 37 heifers over two years. Heifers were synchronized using the previously mentioned protocol with split-time AI. Semen was collected and sexed to favor heifer progeny at an expected ratio of 9:1. The sexing process has been shown to decrease pregnancy rate due to sperm damage and decreased quantity. Semen from 3 random bulls were pooled together making 4 pools or 3 pools of multi-sire semen straws in year 1 and 2 respectively. Multi-sire sexed semen was only administered to heifers who exhibited estrus. The observed ultrasound determined pregnancy rate of heifers administered multi-sire sexed semen was 65% in year 1 and 75% in year 2, which is 12% and 22% greater than the average pregnancy rate reported in previous studies using single-sire sexed semen. Observed differences lends credence to the possibility of improving pregnancy rate by utilizing multiple sires for AI when semen quality is lower. Ultimately these two studies may suggest that multiple sires may outperform pregnancy rate of single sires to AI. This difference may be more pronounced when semen quality is lower. Further research into semen quality of single sires and pooled semen could lead to optimization of fertilization among individuals within a herd.

Sire Distribution of Calves in a Beef Herd with Use of Fixed Time Artificial Insemination Followed by Immediate Bull Exposure for Natural Service in Cows and Heifers

Objective: Our objective was to determine the relative percentages of calves sired by either natural service sire or fixed time artificial insemination (FTAI) sire within the same estrous period.

Inclusion of sire by herd interaction effect in the genomic evaluation for weaning weight of American Angus.

A spurious negative genetic correlation between direct and maternal effects of weaning weight (WW) in beef cattle has historically been problematic for researchers and industry. Previous research has suggested the covariance between sires and herds may be contributing to this relationship. The objective of this study was to estimate the variance components (VC) for WW in American Angus with and without sire by herd (S×H) interaction effect when genomic information is used or not. Five subsets of ~100k animals for each subset were used. When genomic information was included, genotypes were added for 15,637 animals. Five replicates were performed. Four different models were tested, namely, M1: without S×H interaction effect and with covariance between direct and maternal effect () ≠ 0; M2: with S×H interaction effect and ≠ 0; M3: without S×H interaction effect and with = 0; M4: with S×H interaction effect and = 0. VC were estimated using the restricted maximum likelihood (REML) and single-step genomic REML (ssGREML) with the average information algorithm. Breeding values were computed using single-step genomic BLUP for the models above and one additional model, which had the covariance zeroed after the estimation of VC (M5). The ability of each model to predict future breeding values was investigated with the linear regression method. Under REML, when the S×H interaction effect was added to the model, both direct and maternal genetic variances were greatly reduced, and the negative covariance became positive (i.e., when moving from M1 to M2). Similar patterns were observed under ssGREML, but with less reduction in the direct and maternal genetic variances and still a negative covariance. Models with the S×H interaction effect (M2 and M4) had a better fit according to the Akaike information criteria. Breeding values from those models were more accurate and had less bias than the other three models. The rankings and breeding values of artificial insemination sires (N = 1,977) greatly changed when the S×H interaction effect was fit in the model. Although the S×H interaction effect accounted for 3% to 5% of the total phenotypic variance and improved the model fit, this change in the evaluation model will cause severe reranking among animals.

Sire contribution to fertilization failure and early embryo survival in cattle

Despite passing routine laboratory tests of semen quality, bulls used in artificial insemination (AI) exhibit a significant range in field fertility. The objective of this study was to determine whether subfertility in AI bulls is due to issues of sperm transport to the site of fertilization, fertilization failure, or failure of early embryo or conceptus development. In experiment 1, Holstein-Friesian bulls (3 high fertility, HF, and 3 low fertility, LF) were selected from the national population of AI bulls based on adjusted fertility scores from a minimum of 500 inseminations (HF: +4.37% and LF: -12.7%; mean = 0%). Superovulated beef heifers were blocked based on estimated number of follicles at the time of AI and inseminated with semen from HF or LF bulls (n = 3-4 heifers per bull; total 19 heifers). Following slaughter 7 d later, the number of corpora lutea was counted and the uteri were flushed. Recovered structures (oocytes/embryos) were classified according to developmental stage and stained with 4',6-diamidino-2-phenylindole to assess number of cells and accessory sperm. Overall recovery rate (total structures recovered/total corpora lutea) was 52.6% and was not different between groups. Mean (± standard error of the mean) number of embryos recovered per recipient was 8.7 ± 5.2 and 9.4 ± 5.5 for HF and LF, respectively. Overall fertilization rate of recovered structures was not different between groups. However, more embryos were at advanced stages of development (all blastocyst stages combined), reflected in a greater mean embryo cell number on d 7 for HF versus LF bulls. Number of accessory sperm was greater for embryos derived from HF than for LF bulls. The aim of experiment 2 was to evaluate the effect of sire fertility on survival of bovine embryos to d 15. Day 7 blastocysts were produced in vitro using semen from the same HF (n = 3) and LF (n = 3) bulls and transferred in groups of 5-10 to synchronized heifers (n = 7 heifers per bull; total 42 heifers). Conceptus recovery rate on d 15 was higher in HF (59.4%,) versus LF (45.0%). Mean length of recovered conceptuses for HF bulls was not affected by fertility status. In conclusion, while differences in field fertility among AI sires used in this study were not reflected in fertilization rate, differences in embryo quality were apparent as early as d 7. These differences likely contributed to the higher proportion of conceptuses surviving to d 15 in HF bulls.

Artificial insemination of cattle: Description and assessment of a training program for veterinary students

The objective was to assess the effectiveness of a comprehensive artificial insemination (AI) training program designed to facilitate an understanding of the breadth of the AI process, including AI skill acquisition, for preclinical veterinary students. Participants (n = 303) were enrolled at the Ross University School of Veterinary Medicine (Basseterre, St. Kitts, West Indies). The 2-d AI training program (n = 20) consisted of ∼8 h of instruction and ∼8 h of demonstration and hands-on activity. Oral presentations were used to deliver educational content, followed by video clips, discussion, demonstrations, and hands-on activity. Reproductive anatomy and physiology of the estrous cycle, AI sire acquisition, collection, evaluation, cryopreservation and distribution of conventional and sexed semen, storage and handling of frozen semen, use of synchronization protocols, accurate and efficient detection of estrus, and correct AI technique were discussed. True or false pre- and posttests were used to determine the level of knowledge gained by participants during the AI training program. Preclinical veterinary students were required to complete a semen handling and AI technique practical exam to achieve a certificate of completion. Participant program evaluations conducted at the conclusion of the program indicated that veterinary students found the content, structure, discussion, demonstrations, and hands-on activities to be appropriate and useful. No negative comments were offered about the training program, instructor, or activity coinstructors. The AI training program increased the posttest knowledge scores of veterinary students by 22 percentage points. Only 1 participant was unable to achieve a certificate of completion due to failure of the semen handling and AI technique practical exam. These results provide evidence that the AI training program was relevant and effective and that it offered information and skill acquisition with immediate field application.

Pregnancy outcome of lactating dairy cows assigned for Presynch-Ovsynch synchronization program and inseminated either at detected standing heat or at scheduled fixed time

Objective: To determine if insemination at standing heat results in a similar or higher pregnancy rate compared with fixed time artificial insemination, and to study some factors affecting the pregnancy rate. Methods: A total of 8 944 inseminations were included in this study, from which 6 823 inseminations were done in Holstein cows and 2 121 inseminations were performed in Simmental cows. All cows were subjected to a Presynch-Ovsynch protocol. Cows detected in estrus (n=7 424) were artificially inseminated, whereas cows not observed in estrus (n=1 520) were submitted to fixed time artificial insemination. Results: The overall pregnancy rate of cows inseminated on the basis of the detected standing heat was comparable to that recorded for cows receiving fixed time artificial insemination. A higher pregnancy rate was recorded for cows during cold months than that recorded during hot months (P=0.000). A higher pregnancy rate was recorded for Simmental compared with that recorded for Holstein cows (P=0.001). Regarding parity, significant differences in the pregnancy rate were detected between primiparous and multiparous cows (P=0.040). In addition, artificial insemination technicians had no sigificant effect on pregnancy rate (P>0.05). Meanwhile, the used artificial insemination sires significantly (P=0.000) impacted the pregnancy rate. Conclusions: Insemination of cows detected in standing heat prior to predetermined fixed time results in similar pregnancy outcome and decreases days to the first service compared with insemination at the scheduled fixed time at the end of the Presynch-Ovsynch synchronization program. The overall pregnancy outcome is not affected by the breeding program, but it is highly impacted by cow’s breed, parity, artificial insemination sire and breeding season.

Evaluation of genetic structure across U.S. climate zones using prominent AI sires of Red Angus cattle

Climate variability can influence cattle performance. Therefore, the objective of this research was to determine fine-scale genetic diversity in Red Angus cattle in relation to climate zones. One hundred and seventy-five prominent Red Angus artificial insemination (AI) sires were sampled from five conterminous U.S. climate regions (Cool Arid, Cool Humid, Transition Zone, Warm Arid, and Warm Humid). Quantitative and molecular genetic approaches were used to evaluate genetic diversity for the cattle. The first method utilized neutral SNP to determine the genetic structure of the population. The second method used 66 SNP associated with traits potentially influenced by climate (body weight, heat stress, milk yield, heifer conception rate, and early embryonic survival) to detect loci under selection in each zone. Using 13,961 SNP, the genetic structure analysis revealed that there were eight sub-populations present within Red Angus. Furthermore, 23 of the 66 SNP were not in Hardy-Weinberg Equilibrium and loci under selection tests (P < 0.05). Chi-square tests revealed 7 of the 23 SNP to differ (P < 0.008) among climate zones. In conclusion, fine genetic substructure observed in Red Angus corresponded to U.S. climate zones. By identifying the genetic diversity within a prominent Bos taurus beef breed in relation to climate, management strategies can be implemented to utilize the genetic diversity of this breed to adapt to changing climates.

Short communication: Genetic lag represents commercial herd genetic merit more accurately than the 4-path selection model

Expectation of genetic merit in commercial dairy herds is routinely estimated using a 4-path genetic selection model that was derived for a closed population, but commercial herds using artificial insemination sires are not closed. The 4-path model also predicts a higher rate of genetic progress in elite herds that provide artificial insemination sires than in commercial herds that use such sires, which counters other theoretical assumptions and observations of realized genetic responses. The aim of this work is to clarify whether genetic merit in commercial herds is more accurately reflected under the assumptions of the 4-path genetic response formula or by a genetic lag formula. We demonstrate by tracing the transmission of genetic merit from parents to offspring that the rate of genetic progress in commercial dairy farms is expected to be the same as that in the genetic nucleus. The lag in genetic merit between the nucleus and commercial farms is a function of sire and dam generation interval, the rate of genetic progress in elite artificial insemination herds, and genetic merit of sires and dams. To predict how strategies such as the use of young versus daughter-proven sires, culling heifers following genomic testing, or selective use of sexed semen will alter genetic merit in commercial herds, genetic merit expectations for commercial herds should be modeled using genetic lag expectations.

Short communication: Two dominant paternal lineages for North American Jersey artificial insemination sires

Jersey cattle are the second most prominent breed in the United States and represent a growing portion of the dairy cow population in the United States. The objectives of our study were to determine the male lineages of Jersey sires with official genetic evaluations and to determine whether there are differences in sire conception rate among lineages. Paternal lineages back to the 1950s were extracted from genetic evaluation files of the Council on Dairy Cattle Breeding (CDCB, Bowie, MD) for all sires with an official United States genetic evaluation and that were enrolled with the National Association of Animal Breeders (Madison, WI). Further tracing of male lineages was performed by accessing the pedigree database of Jersey Origins LLC (Stitzer, WI). Only paternal lineages were considered because we were interested in transmission of the Y chromosome. Sire conception rate evaluations were also retrieved from CDCB for 1,116 bulls. Nearly all North American bulls born in the decade beginning 2010 could be traced to Secret Signal Observer or Advancer Sleeping Jester, who together account for 98.9% of paternal lineages. Both bulls plus the 3 additional bulls that account for the remaining 1.1% of current descendants can be traced to a single bull (Champion Flying Fox) born on the island of Jersey in 1898. When considering sires imported into the United States, the majority (71%) trace their paternal lineage to Secret Signal Observer or Advancer Sleeping Jester, and 97% can be traced to Champion Flying Fox. Sire conception rates were higher by 0.30 percentage points in the Secret Signal Observer line than in the Advancer Sleeping Jester line, which was significant. The small number of paternal lineages for recently born artificial insemination Jersey sires indicates that there is limited genetic diversity for much of the Y chromosome, suggesting that autosomal variation may be a more important source for differences in male fertility than the Y chromosome.

A nonsense mutation in the COL7A1 gene causes epidermolysis bullosa in Vorderwald cattle.

BackgroundThe widespread use of individual sires for artificial insemination promotes the propagation of recessive conditions. Inadvertent matings between unnoticed carriers of deleterious alleles may result in the manifestation of fatal phenotypes in their progeny. Breeding consultants and farmers reported on Vorderwald calves with a congenital skin disease. The clinical findings in affected calves were compatible with epidermolysis bullosa.ResultsPedigree analysis indicated autosomal recessive inheritance of epidermolysis bullosa in Vorderwald cattle. We genotyped two diseased and 41 healthy animals at 41,436 single nucleotide polymorphisms and performed whole-genome haplotype-based association testing, which allowed us to map the locus responsible for the skin disease to the distal end of bovine chromosome 22 (P = 8.0 × 10−14). The analysis of whole-genome re-sequencing data of one diseased calf, three obligate mutation carriers and 1682 healthy animals from various bovine breeds revealed a nonsense mutation (rs876174537, p.Arg1588X) in the COL7A1 gene that segregates with the disease. The same mutation was previously detected in three calves with dystrophic epidermolysis bullosa from the Rotes Höhenvieh cattle breed. We show that diseased animals from Vorderwald and Rotes Höhenvieh cattle are identical by descent for an 8.72 Mb haplotype encompassing rs876174537 indicating they inherited the deleterious allele from a recent common ancestor.ConclusionsAutosomal recessive epidermolysis bullosa in Vorderwald and Rotes Höhenvieh cattle is caused by a nonsense mutation in the COL7A1 gene. Our findings demonstrate that deleterious alleles may segregate across cattle populations without apparent admixture. The identification of the causal mutation now enables the reliable detection of carrier animals. Genome-based mating strategies can avoid inadvertent matings of carrier animals thereby preventing the birth of homozygous calves that suffer from a painful skin disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0458-2) contains supplementary material, which is available to authorized users.

A genome-wide association study for genetic susceptibility to Mycobacterium bovis infection in dairy cattle identifies a susceptibility QTL on chromosome 23.

BackgroundBovine tuberculosis (bTB) infection in cattle is a significant economic concern in many countries, with annual costs to the UK and Irish governments of approximately €190 million and €63 million, respectively, for bTB control. The existence of host additive and non-additive genetic components to bTB susceptibility has been established.MethodsTwo approaches i.e. single-SNP (single nucleotide polymorphism) regression and a Bayesian method were applied to genome-wide association studies (GWAS) using high-density SNP genotypes (n = 597,144 SNPs) from 841 dairy artificial insemination (AI) sires. Deregressed estimated breeding values for bTB susceptibility were used as the quantitative dependent variable. Network analysis was performed using the quantitative trait loci (QTL) that were identified as significant in the single-SNP regression and Bayesian analyses separately. In addition, an identity-by-descent analysis was performed on a subset of the most prolific sires in the dataset that showed contrasting prevalences of bTB infection in daughters.ResultsA significant QTL region was identified on BTA23 (P value >1 × 10−5, Bayes factor >10) across all analyses. Sires with the minor allele (minor allele frequency = 0.136) for this QTL on BTA23 had estimated breeding values that conferred a greater susceptibility to bTB infection than those that were homozygous for the major allele. Imputation of the regions that flank this QTL on BTA23 to full sequence indicated that the most significant associations were located within introns of the FKBP5 gene.ConclusionsA genomic region on BTA23 that is strongly associated with host susceptibility to bTB infection was identified. This region contained FKBP5, a gene involved in the TNFα/NFκ-B signalling pathway, which is a major biological pathway associated with immune response. Although there is no study that validates this region in the literature, our approach represents one of the most powerful studies for the analysis of bTB susceptibility to date.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-016-0197-x) contains supplementary material, which is available to authorized users.

Fertility after two doses of PGF2α concurrently or at 6-hour interval on the day of CIDR removal in 5-day CO-Synch progesterone-based synchronization protocols in beef heifers

Timed artificial insemination protocols in beef cattle are designed to synchronize ovulation in a greater proportion of females while simultaneously achieving acceptable pregnancy rates and a concise calving season. Protocols achieving such goals reduce time and labor associated with estrus detection and make advanced reproductive technologies implementable for beef producers. The objective of the study was to determine the effect of three different PGF2α (PGF) dosage schemes on artificial insemination (AI) pregnancy rates in beef heifers. We hypothesized that two doses of PGF administered concurrently at the time of controlled internal drug release (CIDR) removal would attain similar pregnancy rates compared with two doses given 6-hours apart—one at CIDR removal and the next 6 hours later in the 5-day CO-Synch progesterone-based synchronization protocol. Angus heifers (n = 875) at six locations in Washington, Idaho, and Oregon states were included in this study. Heifers within locations were assigned a body condition score (BCS). All heifers received a CIDR (1.38 g of progesterone) and 100 μg IM of GnRH on Day 0. The CIDRs were removed on Day 5, heifers were randomly allocated to one of three protocol groups: 1PGF (n = 291), received 25 mg IM of dinoprost (PGF); 2CO-PGF (n = 291), received 50 mg IM of dinoprost at CIDR removal, 2PGF (n = 293), received 25 mg IM of dinoprost at CIDR removal, and an additional 25 mg IM of dinoprost 6 hours later. Each heifer was given GnRH (100 μg, IM) and artificially inseminated at 56 hours after CIDR removal. Heifers were examined for pregnancy status between 50 and 70 days after AI to determine time of conception. A mixed-model procedure (PROC GLIMMIX of SAS) was used to evaluate the effect of treatments (1PGF, 2CO-PGF, and 2PGF) on AI pregnancy rates. Models included were treatments, BCS categories (≤5 and >5), and treatment by BCS category interaction. Location (state), handling facilities, handlers, inseminators, and AI sires were included as a random effect in the model. The 2PGF group had greater AI pregnancy rate of 63.6% (185/291), compared with the 2CO-PGF group at 51.9% (151/291) and 1PGF group at 54.9% (161/293; P < 0.001). An AI pregnancy rate of 50% (104/208) was observed for heifers with BCS less than or equal to 5 versus 58.9% (393/667) for heifers with BCS greater than 5 (P < 0.05). Location did not influence the AI pregnancy rate (P > 0.1). In conclusion, beef heifers received two 25-mg doses of PGF at 6-hour interval on Day 5 at CIDR insert removal in a 5-day CO-Synch + CIDR synchronization protocols achieved greater pregnancy compared with heifers received 50 mg of PGF concurrently at CIDR removal.

Estudo preliminar sobre a extensão do desequilíbrio de ligação e estimativas de autozigose em bovinos leiteiros da raça Gir

Genótipos de 25 touros usados em inseminação artificial foram utilizados para estudar a extensão do desequilíbrio de ligação (LD) e a correspondência entre estimadores de endogamia baseados na informação de pedigree e de SNP da raça Gir no Brasil. No total, 24.020 SNPs tiveram frequências do alelo menor (MAF) maiores que 5 % e foram usados para calcular duas medidas de LD (r² and D’) para todos os pares de marcadores em cada autossomo. LD também foi utilizado para estimar o tamanho efetivo populacional (Ne) da população ancestral em diferentes gerações passadas. Coeficientes de endogamia individuais (F) foram estimados usando informação genealógica (Fped, pedigree de 9 gerações) ou informação de marcadores. As estimativas de F baseadas em marcadores foram obtidas com base no excesso de homozigose (Fhet) em marcadores SNP e a proporção estimada do genoma localizada em trilhas de homozigose (runs of homozigosity, Froh). O LD médio entre marcadores adjacentes de todos os autossomos foi de aproximadamente 0,20 e 0,75, estimado de acordo com as estatísticas r2 e D’. Nesta amostra analisada da raça Gir, verificou-se a existência de LD potencialmente útil para seleção genômica (r²&gt;0,30) no caso de pares de marcadores separados por até 100kb. O tamanho efetivo populacional apresentou uma tendência consistente de queda ao longo do tempo, chegando abaixo de 56 nas últimas três gerações. Uma fraca correspondência entre as estimativas de endogamia individuais baseadas nas trilhas de homozigose e pedigree foi verificada neste estudo (correlações estimadas entre Fped e Froh variaram de 0,32 a 0,42). Os presentes resultados sugerem a possibilidade de aplicação da seleção genômica na raça Gir no Brasil, mas são necessários mais estudos sobre a extensão do desequilíbrio de ligação usando uma maior amostra desta população.

A study based on records taken at time of hoof trimming reveals a strong association between the IQ motif-containing GTPase-activating protein 1 (IQGAP1) gene and sole hemorrhage in Holstein cattle

Feet and leg problems have a major effect on the well-being and lifespan of the dairy cow and thus are economically important to the dairy farmer. Apart from approaches using genetic selection for classical traits from conformation scoring, attempts for genetic improvement can be based either on records of individual disease cases or on records of disorder status at time of hoof trimming. In this study, 1,962 first-lactation cows were subjected to hoof trimming with an assessment of disorder status for sole hemorrhage as a binary trait. Cows were from 7 large commercial herds in Mecklenburg-Western Pomerania (northeastern Germany) that had similar housing with cubicles, slatted flooring, little use of straw for bedding, and total mixed ration feeding. Cows were trimmed and assessed once, focusing on cows in the first half of the lactation. Herds were visited at intervals to enable recording of cohorts at a similar stage of lactation. Each cohort or herd-visit included between 31 and 165 cows. Additional measurements included body weight, back fat thickness, and body condition at time of trimming. Further data on dairy production, conformation scores, and reproductive performance were merged after collection of records had finished. The DNA extracted from blood of 1,183 cows was used for analysis with a custom-made array of 384 single nucleotide polymorphisms (SNP). The SNP were selected according to results from the literature for effects in classical conformation traits, from biochemical pathway analysis, and from comparative analysis of putative candidate genes in cattle, pigs, and sheep. Selection of cohorts of cows for SNP chip analysis was such that cohorts with extreme frequencies of disorders and cohorts with slightly deviating housing systems were excluded in this first step. The results from a mixed threshold model analysis with genotype included as a fixed effect and accounting for relationships among animals revealed that the intronic SNP rs29017173 (A/G) within the IQ motif-containing GTPase-activating protein 1 (IQGAP1, Bos taurus autosome 21) was significantly associated with disorder status. Back-transformed means of disorder status for the 3 genotypes were 0.37 (AA), 0.52 (AG), and 0.56 (GG). Using the full data set of 1,962 cows, including the less-suitable cohorts, gave back-transformed means of 0.51 (AA), 0.58 (AG), and 0.62 (GG). As SNP rs29017173 is included on the Illumina BovineSNP50 DNA Analysis BeadChip (Illumina Inc., San Diego, CA), a sample of 2,394 artificial insemination sires from the German calibration sample for genomic selection from birth years 1998 to 2003 was studied for possible correlated effects. The A/G polymorphism of SNP rs29017173 studied here was also associated with substantial effects for feet and leg traits from the classical conformation score system. Selection using this polymorphism will be facilitated by the fact that the same allele is favored for all traits with substantial effects.

Genetic analysis of the Fourier-transform infrared spectra of bovine milk with emphasis on individual wavelengths related to specific chemical bonds

Fourier-transform infrared (FTIR) spectra are used to predict the fat, protein, casein, and lactose contents of milk. These estimates are currently used to predict the individual estimated breeding values of animals. The objective of the present study was to estimate the genetic variation and heritabilities of the milk transmittance spectrum at each individual FTIR wave. Milk was sampled once per cow from a total of 1,064 Italian Brown Swiss cows from 30 herds, sired by 50 artificial insemination sires. The FTIR spectra of all samples were collected within 3h of sampling from 25mL of milk. The obtained spectral range comprised wavenumbers 5,000 to 930×cm−1, corresponding to wavelengths 2.00 to 10.76μm and frequencies from 149.9 to 27.9THz, for a total of 1,056 waves. These were acquired using a MilkoScan FT120 FTIR interferometer (Foss Electric A/S, Hillerød, Denmark). Each spectral data point was treated as a single trait and analyzed using an animal model REML method. The results indicated that the transmittance of the bovine milk FTIR spectrum was heritable for most individual waves in the wavenumber interval from 5,000 to 930×cm−1. Moreover, the transmittance of contiguous FTIR waves was much more highly correlated in terms of the average value and phenotypic variation, compared with genetic variation. In the present study, we characterized 5 regions of the FTIR spectrum that were relevant to the analysis of milk; 2 regions, one in the transition area between the short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) divisions of the electromagnetic spectrum (SWIR-MWIR region) and another very short region in the MWIR division (MWIR-2 region), were characterized by very high phenotypic variability in the transmittance of individual milk samples within each wave. This was caused by the absorption peaks of water, which can mask the effects of other important milk components. These regions also showed high genetic variability in transmittance, and the heritability estimates of individual waves were generally very low (with some exceptions). The 3 other identified regions contained many transmittance peaks that represented important chemical bonds; these showed much lower phenotypic and genetic variability in terms of individual waves, but relatively higher and less variable heritability estimates. Among them, the SWIR region (near-infrared) showed a peculiar cyclic pattern of the heritability coefficients of transmittance, the MWIR-1 region was particularly important for the estimation of fat, and the MWIR-LWIR region (also known also as the “fingerprint region”) had 3 areas of relatively high heritability. In summary, we found that the transmittance data from the FTIR spectra of milk have genetic variability that may prove useful for the direct genetic improvement of dairy species, rather than only through indirect phenotypic predictions of individual milk quality and technological traits.

Maternity validation using sire‐only BovineSNP50 BeadChip data

Based on pairwise identity-by-state (IBS) distances and whole-genome SNP data, kinship was investigated in the Israeli Holstein population. A total of 789 bulls, including most of the artificial insemination sires in service since 1987, were genotyped by the BovineSNP50 BeadChip. This sample included up to five generations. For each bull-by-bull combination, three states are possible for each marker: no match, a single match and both alleles match. Summing over all markers, the 932598 IBS scores (three match frequencies*310866 bull-by-bull combinations) were visualized using three-dimensional coordinates that corresponded to the frequencies of the three possible states. Results were reduced to two dimensions using the transformations x'=0.7071(1+freq1-freq2) and y'=1.2247freq0. Bull-by-bull pairs were grouped according to their level of kinship, and canonical scores were calculated using discriminant analysis and the x' and y' features. Of the 474 pairs of recorded maternal grandsire-grandson with both individuals genotyped, the probability for 28 pairs to belong to this level of kinship was low (P<0.05), suggesting an error rate of around 3% per generation in pedigree determination.

Biomarker-Based Nanotechnology for the Improvement of Reproductive Performance in Beef and Dairy Cattle

Reproductive performance of livestock animals, including dairy and beef cattle, influences the productivity of agriculture in the US and worldwide. Artificial insemination (AI) is one technology with great potential to improve livestock reproductive efficiency. Particularly, gains in reproductive performance of AI sires can be made by identifying and eliminating bulls with inferior fertility/semen quality by testing and discarding individual semen collections/ejaculates with inferior fertilization potential and by eliminating defective spermatozoa from semen collected for AI. Both sire fertility testing and semen purification can potentially be improved through the application of nanotechnology. The necessary first step in this process is the identification and validation of sperm quality biomarkers; they are the differentially expressed sperm-borne proteins/ligands that can be objectively quantitated to measure sperm quality and to estimate future fertility. Proteins expressed on the sperm surface can be targeted using magnetic nanoparticles to allow for rapid, efficient removal of defective spermatozoa from semen. This article reviews recent progress in the identification of such biomarkers (e.g., ligands of lectins from Arachis hypogaea and Lens culinaris, sperm proteins ubiquitin and post-acrosomal, WW domain-binding protein [PAWP]), and also describes recent trials of nanoparticle-based technologies for fertility testing and the nanopurification of bull semen for commercial AI.

Accuracy of direct genomic breeding values for nationally evaluated traits in US Limousin and Simmental beef cattle

BackgroundIn national evaluations, direct genomic breeding values can be considered as correlated traits to those for which phenotypes are available for traditional estimation of breeding values. For this purpose, estimates of the accuracy of direct genomic breeding values expressed as genetic correlations between traits and their respective direct genomic breeding values are required.MethodsWe derived direct genomic breeding values for 2239 registered Limousin and 2703 registered Simmental beef cattle genotyped with either the Illumina BovineSNP50 BeadChip or the Illumina BovineHD BeadChip. For the 264 Simmental animals that were genotyped with the BovineHD BeadChip, genotypes for markers present on the BovineSNP50 BeadChip were extracted. Deregressed estimated breeding values were used as observations in weighted analyses that estimated marker effects to derive direct genomic breeding values for each breed. For each breed, genotyped individuals were clustered into five groups using K-means clustering, with the aim of increasing within-group and decreasing between-group pedigree relationships. Cross-validation was performed five times for each breed, using four groups for training and the fifth group for validation. For each trait, we then applied a weighted bivariate analysis of the direct genomic breeding values of genotyped animals from all five validation sets and their corresponding deregressed estimated breeding values to estimate variance and covariance components.ResultsAfter minimizing relationships between training and validation groups, estimated genetic correlations between each trait and its direct genomic breeding values ranged from 0.39 to 0.76 in Limousin and from 0.29 to 0.65 in Simmental. The efficiency of selection based on direct genomic breeding values relative to selection based on parent average information ranged from 0.68 to 1.28 in genotyped Limousin and from 0.51 to 1.44 in genotyped Simmental animals. The efficiencies were higher for 323 non-genotyped young Simmental animals, born after January 2012, and ranged from 0.60 to 2.04.ConclusionsDirect genomic breeding values show promise for routine use by Limousin and Simmental breeders to improve the accuracy of predicted genetic merit of their animals at a young age and increase response to selection. Benefits from selecting on direct genomic breeding values are greater for breeders who use natural mating sires in their herds than for those who use artificial insemination sires. Producers with unregistered commercial Limousin and Simmental cattle could also benefit from being able to identify genetically superior animals in their herds, an opportunity that has in the past been limited to seed stock animals.

Factors affecting daughters distribution among progeny testing Holstein bulls

The aim of this study was to investigate factors influencing the number of daughters of Holstein bulls during the progeny testing using data provided by the Italian Holstein Friesian Cattle Breeders Association. The hypothesis is that there are no differences among artificial insemination studs (AIS) on the daughters distribution among progeny testing bulls. For each bull and beginning from 21 months of age, the distribution of daughters over the progeny testing period was calculated. Data were available on 1973 bulls born between 1986 and 2004, progeny tested in Italy and with at least 4 paternal half-sibs. On average, bulls exited the genetic centre at 11.3±1.1 months and reached their first official genetic proof at 58.0±3.1 months of age. An analysis of variance was performed on the cumulative frequency of daughters at 24, 36, 48, and 60 months. The generalized linear model included the fixed effects of year of birth of the bull (18 levels), artificial insemination stud (4 levels) and sire of bull (137 levels). All effects significantly affected the variability of studied traits. Artificial insemination stud was the most important source of variation, followed by year of birth and sire of bull. Significant differences among AI studs exist, probably reflecting different strategies adopted during progeny testing.