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• Six SNP on BTA 23 were associated with lean or overall maturity of carcasses. • A single SNP was associated with skeletal maturity on BTA 1. • Associated SNP: marbling score (BTA 12; n = 2) and carcass weight (BTA 14; n = 2). • Electrical stimulation may inhibit detection of SNP-trait associations. • Carcass traits had low or no relationships with measured temperament traits. Genome-wide association analyses were conducted using SNP and carcass traits, with and without electrical stimulation separately, of 350 Bos indicus-Bos taurus steers from a designed mapping population consisting of full-sibling families (embryo transfer) and half-sibling families. Four F 1 Nellore–Angus sires had progeny in both types of families. Relationships of carcass traits with multiple assessments of temperament (correlation coefficients of unadjusted or residual values), including aggressiveness (willingness to hit an evaluator), nervousness, flightiness (nervousness with running or other movement), gregariousness (willingness to separate from other steers), and overall temperament (all temperament traits assigned as 1 to 9 values; higher numbers indicate worse or less desirable temperament) at 1 year of age and with overall temperament evaluated immediately prior to slaughter were low (0 < | r | < 0.18). Significant SNP associations were detected (False Discovery Rate controlled at 0.05) on BTA 1 with skeletal maturity (n = 1), and BTA 14 (n = 2) with carcass weight. Candidate genes were (skeletal maturity) phospholipase C like 2 (PLCL2) and (carcass weight) neutral sphingomyelinase activation associated factor (NSMAF) and thymocyte selection associated high mobility group box (TOX). Two SNP with association with marbling score were identified on BTA 12— dachshund family transcription factor 1 (DACH1) was a candidate gene. A region from 24.25 to 38.54 Mb on BTA 23 contained 6 SNP with significant associations with lean or overall maturity, which may be the first reported for these traits. Candidate genes on that chromosome included fibrocystin/polyductin (PKHD1), glial cells missing homolog 1 (GCM1) , prolactin (PRL), and ring finger protein 144B (RNF144B). All detections of association were in traits measured on the side with no electrical stimulation; it may be that electrical stimulation removes some of the variation permitting detection of association. [ABSTRACT FROM AUTHOR]

Highlights • We estimated genetic parameters for male and female reproductive traits. • Our focus was on genetic correlations with scrotal circumference at different ages. • Age at first calving correlated strongly with earlier scrotal circumference measurements. • In turn, adult scrotal circumference was poorly correlated with age at first calving. • We conclude scrotal circumference should be recorded earlier in breeding programs. Abstract In cow-calf operations the moment the heifer achieves her first pregnancy set up her future productivity. Although puberty itself is a yes-or-no condition, time to the event has a quantitative genetic basis and thus is suitable for genetic selection. However, the trait is difficult to measure directly and proxies such as age at first calving (AFC), or scrotal circumference (SC), are typically used. In genetic evaluations, the age at which SC is measured usually corresponds to last part of pubertal development phase. But given that initiation of puberty in both sexes is controlled by the same neuroendocrine mechanisms, we argue that an earlier measurement, taken instead at the start of the pubertal development phase, is probably a better indicator of female precocity. To support the hypothesis, we fitted a multiple-trait animal model on AFC records and SC measurements taken at 300, 400, and 630 days of age and estimated heritabilities and genetic correlations by REML. Importantly, usually AFC data is afflicted by the problem that when breeding season starts most heifers are already cycling (which is, of course, the desired condition) and thus the record poorly reflects precocity. To avoid the problem, in this study we used records collected from an Angus herd in which heifers receive an early natural first service at 375 days of age. Genetic correlation between AFC and SC300 was twice as large as the one corresponding to SC400 (–0.478 ± 0.13 vs –0.244 ± 0.11) and three times larger than to SC630 (–0.478 ± 0.13 vs –0.152 ± 0.12), a result that supports our hypothesis. Heritabilities for SC300, SC400 and SC630 were 0.429 ± 0.07, 0.704 ± 0.07 and 0.576 ± 0.08, respectively, and 0.371 ± 0.05 for AFC. Our results have an important implication in the age at which SC, as an indirect trait for improving precocity, is typically measured in beef cattle breeding programs. Indeed, they indicate that measurements should be taken earlier. [ABSTRACT FROM AUTHOR]

• Male-sexed semen can increase numbers of heavier and faster-growing male offspring • Artificial insemination is not commonly practised in extensive beef cow herds • Sexed semen increased breeding costs by up to 91% compared with natural mating only • Increased income from heavier, male offspring did not justify the higher breeding costs • Male-sexed semen was not profitable for the extensive beef cow herd modelled Male-sexed semen can be used in beef cow herds to increase the number of heavier and faster-growing male offspring. The use of sexed semen requires artificial insemination (AI) which has limited use in extensive beef systems due to practical constraints and the additional breeding costs incurred. The objective of this study was to use bio-economic simulation modelling to predict the profitability of using sexed semen via fixed time AI for a New Zealand hill country farm system based around a beef cow herd. When modelling self-replacing Angus herds male-sexed Simmental semen was utilised across 43% of mixed-age cows then follow up Simmental bulls were used for subsequent natural mating. To generate replacement Angus heifers, first time calvers and remaining mixed-age cows were bred with unsexed Angus semen and then naturally bred with Angus bulls if they did not conceive. All mixed-age cows in an AngusxHolstein-Friesian herd with a bought-in replacements policy were bred with male-sexed Simmental semen followed by Simmental bulls. First time AngusxHolstein-Friesian calvers were bred with unsexed Angus semen followed by Angus bulls. Sire breed was assumed to have the same effects on offspring production regardless of use through AI or natural mating. Herds using sexed semen were assumed to undergo synchronised fixed-time AI which resulted in a more condensed calving spread and 3% heavier average weaning weights due to calves being predominantly male and on average seven days older. Total breeding costs were higher for herds using sexed semen via AI at NZD 135-166 /cow compared with NZD 67-102 /cow for herds using only natural mating. Increases in breeding costs were relatively larger than any additional income for all herds using sexed semen via AI, resulting in lower COS (cash operating surplus) compared with herds using all-natural mating. The COS of using sexed semen via AI were 14% (COS = NZD 280 /ha) and 9% (COS = NZD 405 /ha) lower than all-natural mating using Simmental sires for the purebred Angus (COS = NZD 325 /ha) and AngusxHolstein-Friesian crossbred (COS = NZD 444 /ha) cow herds, respectively. It appears producing more fast-growing male calves through use of sexed semen via AI is not currently an economically feasible option for beef producers under extensive production systems. Future analysis could include benefits of access to higher genetic merit sires as the combination of superior genes and more male offspring may be more profitable than all-natural mating. [ABSTRACT FROM AUTHOR]

Subjective scores ( n =2603) representing (1) the shedding and regrowth of winter coat and (2) total quantity of hair were recorded monthly for 2 yr for 135 Angus cows. Shedding scores of 1 indicated summer coats (all winter coat shed) and 5 indicated complete winter coats. Quantity scores of 1 and 5 indicated minimal and maximal amounts of hair in the coat, respectively. Scores of 2 through 4 for respective traits indicated intermediate conditions. A trigonometric function representing a sinusoid process was fitted to the residuals of scores across time: A sin [ B ( t − C ) ] + D , where A represents the height of peaks in the oscillatory function above a centralized baseline in the Cartesian plane; B represents the angular frequency, that is, the rate of change of scores across a complete fundamental cycle of the process; C represents the horizontal shift in the cycle; D represents the vertical offset of the function. The time dimension in months is represented as t . Parameters for this function were estimated for the two traits using least squares nonlinear regression procedures (1) across all data, (2) within cow age categories, and (3) within groups of cows representing distinct maternal lineages. In all cases, parameters representing amplitude ( A ) and angular frequency ( B ) seemed to be estimated most reliably (as indicated by magnitude of SE) and the parameter representing the vertical offset seemed to be estimated least reliably. The numerically larger estimate of the amplitude parameter ( A ) for winter coat shedding and regrowth score relative to the quantity of hair score suggested that it better characterized the process, as well as differences among cow age groups or maternal lineages. For both traits within all groupings of records the parameter representing the horizontal phase shift ( C ) appeared to be most informative: curves for younger cows were shifted to the right in the time space, indicating later shedding of winter coat. The phase shift parameter also best characterized differences in the process for cows in different maternal lineages; however, numerical differences in the parameter estimates representing amplitude ( A ) and angular frequency ( B ) also appeared to be responsible for the distinctiveness of group curves. Curves visually represented the shedding of winter coats (April–July in the time parameter space) better than the winter regrowth process. There may be value in considering parameters of such curves in some genetic improvement strategies for enhancing cow adaptability to local environmental conditions. [ABSTRACT FROM AUTHOR]

• Using terminal sires in a beef cow herd increases sale prices and feed demand per animal sold. • Selling more of cattle direct to slaughter necessitated reductions in cow herd numbers. • Selling more cattle direct to slaughter was the most economically beneficial strategy explored. • Price premiums and higher weaning rates were also economically beneficial. • These management options can be implemented concurrently in a beef cow herd. New Zealand farmers can choose to breed a proportion of their beef cow breeding herd with terminal breed sires to produce heavier offspring to sell for higher per head prices. However, the heavier weights of terminal offspring also increase their feed demand which may necessitate cow herd size reductions in a system with a fixed feed supply. This study used a bio-economic, system dynamics model to simulate cattle numbers, production, and beef enterprise cash operating surplus (COS) for a self-replacing beef suckler herd of Angus breed cows bred with only Angus sires to produce purebred offspring or a proportion of cows bred with European breed terminal sires (such as Charolais or Simmental). The herd was also modelled with varying calf weaning rates (84 or 90%), with offspring sales occurring either at weaning or at 27 months of age, and in a secondary analysis, with or without price premiums for sales of cattle of at least 75% Angus breed. Total annual beef feed demand was maintained at 40% of total farm feed supply (total farm area of 530 ha) in all scenarios, with the remainder consumed by the on-farm sheep flock. Beef enterprise COS was therefore divided by the beef herd proportion of farm area (212 ha) to derive a per ha COS value. Herd replacement rate was first modelled at 22% allowing for 43% of cows to be bred with terminal sires with a weaning rate of 84%. With a weaning rate of 90% the replacement rate was 18% allowing 60% of cows to be bred with terminal sires. The base scenario with a herd weaning rate of 84% using only Angus sires had a COS of NZD 255 /ha. Relative to the base scenario, use of terminal sires increased COS by the largest amount (COS = NZD 317 /ha), Angus premiums increased COS by a lower amount (COS = NZD 307 /ha), and the higher weaning rate of 90% increased COS by a slightly lesser amount (COS = NZD 302 /ha). Alternatively, these strategies could be implemented concurrently, which was predicted to have the highest COS at NZD 381/ha. These results can inform farmer decision making and farmers can consider the relative profitability potential and practicality of the explored strategies for their breeding herd. [ABSTRACT FROM AUTHOR]

• Beef-dairy crossbred cows sourced from the dairy industry can be farmed as a breeding herd for beef production. • Beef-dairy cows have been observed as lighter than Angus cows while weaning heavier calves. • Feed demand, productivity, and profitability of these breed options were compared using bio-economic modelling. • Beef-dairy herds were 8% to 79% more profitable, depending on offspring sale policies and sire breed choice. • Numbers of breeding cows may reduce to levels which are impractical in this system with fixed feed supply on hill country. Beef-dairy crossbred cows (such as Angus-Friesian) have lighter mature cow weights while weaning heavier calves compared with cows in a typical self-replacing New Zealand Angus breed herd. The objective of this study was to quantify the potential profitability of farming an Angus-Friesian cow herd through modelling the potential changes in cattle numbers, feed demand, production, and beef enterprise economics. The Angus-Friesian cow herd was simulated as purchasing all replacement heifers and was modelled with different sire breeds (Angus or terminal such as Charolais or Simmental) and offspring sale policies (sold at weaning at six months of age or at 27 months of age). Total annual cattle feed demand was maintained at the same level for all modelled scenarios. Angus-Friesian herds had 8% to 79% higher beef enterprise cash operating surplus (COS) compared with the self-replacing Angus herd (COS = NZD 255/ha). For the Angus-Friesian herds, selling all offspring prime (direct to slaughter) at 27 months of age resulted in 20% to 59% higher COS than selling all offspring store (sold at weaning) at weaning at six months old. Utilising terminal breed sires with the Angus-Friesian herd resulted in 10% to 12% higher COS compared with using Angus sires when selling all offspring store at weaning, due to the heavier sale weights and resultant higher per head sale values. However, when selling all offspring prime at 27 months of age the utilisation of Angus sires resulted in 10% to 11% higher COS than using terminal sires, as the lighter weights and thus total feed demand was lower for offspring born to Angus sires allowing for a greater breeding cow numbers (and therefore numbers of offspring sold). Scenarios in which offspring were retained on-farm until 27 months of age increased total feed demand of cattle destined for sale, necessitating reductions in breeding cow numbers to as low as 60% of the base system level, which may inhibit farmers' ability to manage pasture quality. Farmers considering a change to an Angus-Friesian crossbred herd of breeding cows can include the potential herd numbers, feed demand, production, and economic changes predicted in this analysis in their decision making, as well as the practicalities of the explored strategies for designing their farm system. [ABSTRACT FROM AUTHOR]

Abstract: The objectives of this study were to characterize rectal temperature and coat score under subtropical North American summer conditions for straightbred and crossbred Romosinuano, Brahman, and Angus cattle, to estimate heterosis and breed direct and maternal effects in a subset of those, and to estimate heritability and genetic correlation of these traits. Records of cows (n=612 cows; 1861 total records) and calves (n=1588) from summer days in subtropical Florida, USA, were evaluated using animal models. Records of cows and calves from 2 management groups were analyzed separately. In the first management group, cows were all straightbred as were their calves; most of these cows were dams of cows in the other management group. Cows in that second management group were produced from all possible matings of Romosinuano, Brahman, and Angus bulls and cows; breed groups were 3 straightbred groups and 3 groups of F1 cows (reciprocal crosses combined). Calves of these cows were 3-breed crosses (all F1 cows were mated to bulls of the 3rd breed) and F1 crosses (straightbred cows were bred in approximately equal numbers to bulls of the other 2 breeds). Angus straightbred and crossbred cows and calves had the highest rectal temperature and coat score (subjective score where larger numbers indicated greater quantity of hair on the coat) means in all 4 analyses. In the second management group (straightbred and crossbred cows raising crossbred calves), Romosinuano straightbreds and F1 Romosinuano–Brahman cows had the lowest (P<0.001) rectal temperature and coat score means. Heterosis for rectal temperature was −0.2±0.05 and −0.24±0.05°C for Romosinuano–Angus and Brahman–Angus, respectively (P<0.001). Heterosis for coat score was −1.4±0.2, −0.9±0.2, and −2±0.2 for Brahman–Angus, Romosinuano–Brahman, and Romosinuano–Angus, respectively (P<0.001). Direct effects of Romosinuano and Brahman reduced rectal temperature and coat score; direct effects of Angus increased both. Estimates of heritability were 0.19±0.03 and 0.27±0.04 for rectal temperature and coat score, respectively. Permanent environmental effects as proportions of phenotypic variance were 0.03±0.02 and 0.17±0.04 for rectal temperature and coat score, respectively. The estimate of genetic correlation of these traits was 0.24±0.09. With respect to these traits, Romosinuano may offer benefits of tropical adaptation at least to the extent of Brahman under Florida summer conditions. [Copyright &y& Elsevier]

• Electrical stimulation of nellore-angus carcasses influenced 5 of 30 steak flavors. • SNP on BTA 4, 5, and 12 were associated with cooked beef lean flavor. • Two SNP (BTA 16 and 23) were associated with acid flavor post electrical stimulation. • One SNP on BTA 11 was associated with metallic flavor post electrical stimulation. • Beef flavor traits had low or no relationships with steer temperament traits. Steaks from Bos indicus -influenced steers (n = 350) were evaluated for beef flavor and aromatic traits. Electrical stimulation status was a fixed effect. Genome-wide association was conducted with 34,957 SNP from a commercial array using a mixed linear model. Significant effects of electrical stimulation were less intense acid and browned flavors, and more intense cooked beef lean and livery flavors (P < 0.05). There were no strong simple or residual correlations among the flavor traits with carcass quantity, quality, sensory panel palatability, or temperament traits of steers. There were 18 (no electrical stimulation; chemical burn, cooked beef lean, livery, sour) and 8 (electrical stimulation; acid, chemical burn, cooked beef lean, metallic) SNP associated with flavor traits (FDR < 0.18). Closest genes to these were involved in neural/neuronal processes or cellular and extracellular structure. [ABSTRACT FROM AUTHOR]

• Nine SNP on BTA 29 were associated with tenderness traits. • One SNP on BTA 4 was associated with juiciness score. • Associations on BTA 29 may be affiliated with CAPN1 , but this was not confirmed. • Electrical stimulation may suppress SNP-connective tissue amount associations. • Palatability traits had low or no relationships with measured temperament traits. Genome wide association analyses were conducted for palatability traits in the presence or absence of electrical stimulation. Palatability traits were measured on steaks from Nellore-Angus steers (n = 350). No palatability traits were correlated (| r | < 0.18) with steer temperament. Nine SNP on BTA 29 from 35.7 Mb to 48.2 Mb were associated with muscle fiber or overall tenderness, and/or connective tissue amount measured on steaks from carcass sides not electrically stimulated. Only three of these SNP were associated with these traits on the electrically stimulated carcass side. Associated SNP with connective tissue amount were only detected in steaks from carcass sides not subjected to electrical stimulation. Sixteen other BTA 29 SNP were associated with at least one tenderness trait from the electrically stimulated carcass side. One SNP on BTA 4 and 24 were associated with juiciness and overall tenderness, respectively. Candidate genes on BTA 29 included EGF containing fibulin extracellular matrix protein 2 (EFEMP), slingshot protein phosphatase 3 (SSH3), achaete-scute family bHLH transcription factor 2 (ASCL2). Although not detected as a candidate gene, the associated SNP with the various tenderness traits on BTA 29 may indicate the importance of calpain 1 (CAPN1), which has been considered influential on beef tenderness. [ABSTRACT FROM AUTHOR]