Terminal Sire Research Articles

Simulating the productivity and profitability of a herd of beef-dairy crossbred breeding cows on New Zealand hill country with fixed feed supply

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.

127. Sheep rumen volume as a methane proxy – terminal sire breed comparison and relationships with breeding values for production traits

127. Sheep rumen volume as a methane proxy – terminal sire breed comparison and relationships with breeding values for production traits

Effects of standardized ileal digestible lysine on growth performance and economic return in duroc-sired finishing pigs.

In the United States, emphasis has shifted toward improved pork quality and has resulted in greater use of Duroc-based terminal sires. Duroc sires have differences in ADG, ADFI, G:F, and carcass leanness compared to other sires. Therefore, our objective was to determine the standardized ileal digestible (SID) Lys estimates for Duroc-based sired finishing pigs. In Exp. 1, 2,124 pigs (DNA 600 ×PIC 1050, initially 48.9 kg) were used with 24–27 pigs per pen and 16 pens per treatment. Corn-soybean meal-based diets were fed in three phases (49–59, 59–71, and 71–81 kg). Pens were randomly allotted to 1 of 5 treatments based as a percentage of PIC (2016) SID Lys estimates for gilts (85%, 95%, 103%, 110%, and 120%). Phase 1 diets were formulated to 0.90%, 1.01%, 1.09%, 1.17%, and 1.27%, phase 2 to 0.79%, 0.87%, 0.94%, 1.03%, and 1.10%, and phase 3 to 0.71%, 0.78%, 0.85%, 0.92%, and 0.99% SID Lys. Increasing SID Lys increased (linear, P < 0.001) ADG and Lys intake/kg of gain. A marginally significant improvement (quadratic, P = 0.071) in G:F was observed as SID Lys increased. Feed cost, feed cost/kg of gain, revenue (linear, P < 0.01) and income over feed cost (IOFC) increased (quadratic, P = 0.045) with increasing SID Lys. In Exp. 2, 2,099 pigs (DNA 600 ×PIC 1050, initially 90.1 kg) were used with 24–27 pigs per pen and 20 pens per treatment. Corn-soybean meal-based diets were fed in 2 phases (90–106 and 106–136 kg). Pens were randomly allotted to 1 of 4 treatments based as a percentage of PIC (2016) SID Lys estimates for gilts (85%, 93%, 100%, and 110%). Phase 1 diets were formulated to 0.65%, 0.71%, 0.77%, and 0.84% and phase 2 to 0.60%, 0.66%, 0.71%, and 0.78% SID Lys. Overall, increasing SID Lys increased (linear, P < 0.05) G:F, Lys intake/kg of gain, live weight and HCW, and increased (quadratic, P = 0.020) ADG. Feed cost (linear, P < 0.01), revenue, and IOFC increased (quadratic, P ≤ 0.053) with increasing SID Lys. In conclusion, the SID Lys estimate for growth and IOFC was 1.19% or 4.63 g SID Lys/Mcal of NE, 1.05% or 4.04 g SID Lys/Mcal of NE, and 0.94% or 3.58 g SID Lys/Mcal of NE for pigs weighing 49–59 kg, 59–71 kg, and 71–81 kg, respectively. The SID Lys estimate for late finishing pigs was 0.74%–0.81% or 2.85–3.10 g SID Lys/Mcal of NE, and 0.69%–0.75% or 2.61–2.84 g SID Lys/Mcal of NE, for 90–106 kg and 106–136 kg pigs, respectively. These data provide SID Lys estimates for current Duroc-sired genetic lines raised in a commercial environment.

Simulating use of terminal sires in a self-replacing beef suckler herd with varying weaning rate, calf sale policies, and price premiums

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.

Field Trial Assessing the Use of Sex-Sorted Semen in Beef Cattle

Objective: The objective was to evaluate the reproductive performance of sex-sorted semen on beef cows and heifers. Study Description: For this trial, 320 Angus and SimAngus cows and heifers from four groups were used. Group 1 yearling heifers (n = 101) were synchronized using the melengestrol acetate plus prostaglandin F2α (MGA-PGF2α) protocol and Groups 2, 3, and 4 cows (n = 219) were synchronized using the 7-Day CO-Synch + CIDR protocol. Insemination was done with semen from an Angus sire (Group 1 yearling heifers and Group 2 young cows) sorted to contain >90% X-bearing sperm, or a Charolais sire (Groups 3 and 4 mature cows) sorted to contain >90% Y-bearing sperm. Females were bred after visual estrus detection (Group 1 yearling heifers), fixed time artificial insemination (AI; Group 4 mature cows), or split time AI (Group 2 young cows and Group 3 mature cows). The Bottom Line: These results indicate that sex-sorted semen has potential in commercial beef cows and heifers. Increasing carcass weights in the beef industry has caused a greater price spread between steers and heifers. With increasing spread in value between heifer calves and steer calves, opportunity exists for economic gain with “bull” sexed semen, especially in terminal sire programs.

PSXII-29 Evaluation of Barbados Blackbelly and St. Croix sheep under accelerated lambing using purebred and terminal sire mating: Lamb survival and body weight

Abstract Objectives were to evaluate lamb survival and body weight (BW) under an accelerated, pasture-lambing system. Lambs were born to Barbados Blackbelly (BB) or St. Croix dams (SC) mated within breed (purebred) or to Dorset (terminal) in single sire mating groups. Lambs were born in April (2013 and 2015), December (2013 and 2015), and August (2014 and 2016) and weaned at 9 weeks of age. Traits considered were BW at birth (BW0; n = 959), 65-d adjusted weaning BW (BW65; n = 788), and survival to weaning (n = 959). Data were analyzed with fixed effects of dam age, sex, birth type, dam breed (BB vs SC), dam mating system (purebred vs terminal), birth month-year, and significant two-way interactions and a random dam effect. Dam breed did not impact BW65 (P = 0.09). While BW0 was greater for lambs born to SC than BB dams (3.44 vs 3.23 kg; P &amp;lt; 0.01), survival to weaning was greater for lambs born to BB than SC dams (0.93 vs. 0.87; P = 0.02). The dam mating system x birth month-year interaction was significant for both BW traits (P ≤ 0.01). Within birth month-year, BW0 was 18 to 24% greater and BW65 was 12 to 24% greater for terminal than purebred lambs (P &amp;lt; 0.01). However, BW0 differences between dam mating systems were greatest for August born lambs whereas BW65 differences were greatest for April born lambs. Lamb survival was not affected by dam mating system or birth month-year (P ≥ 0.27). Using a terminal sire improved BW without affecting survival of lambs reared by landrace hair sheep dams, making this a viable management tool to increase productivity of forage-based production systems.

PSXI-24 Evaluation of Barbados Blackbelly and St. Croix hair sheep under accelerated lambing using purebred and terminal sire mating: Ewe fertility, prolificacy, and productivity

Abstract Objectives were to evaluate ewe performance under an accelerated, pasture-lambing system. Barbados Blackbelly (n = 85) and St. Croix ewes (n = 91) were exposed to rams of their own breed (pure) or Dorset (terminal) in November (2012 and 2014), July (2013 and 2015), and March (2014 and 2016). Traits considered were fertility (i.e., ewes lambing/ewes exposed; n = 670) and number of lambs born (NLB), number of lambs weaned (NLW), and total 65 d adjusted litter weaning weight (LWW; n = 548 each). Data were analyzed with fixed effects of ewe age (1, 1.5, 2 yr, or ≥ 2.5 yr), breed, mating system (pure vs terminal), mating month-year, and the mating system x mating month-year interaction and a random ewe effect. Fertility was greater for Barbados Blackbelly than St. Croix ewes (0.88 vs 0.73; P &amp;lt; 0.01) but ewe breed did not affect any other trait (P ≥ 0.06). The mating system x mating month-year interaction effect impacted all traits (P ≤ 0.03) except NLB (P = 0.09) and performance between mating systems was compared within mating month. Fertility was greater for pure than terminal mated ewes in November (0.96 vs 0.85) and July (0.94 vs 0.53; P ≤ 0.01). Following July mating, both NLB and NLW were greater for pure than terminal mated ewes (1.69 vs 1.37 lambs and 1.43 vs 1.11 lambs, respectively; P &amp;lt; 0.01). However, LWW was greater for terminal than pure mated ewes after November (18.0 vs 15.7 kg) and March mating (18.1 vs 14.2 kg; P ≤ 0.02). Using a terminal sire in landrace hair sheep under accelerated mating generally reduced fertility, NLB, and NLW but improved LWW. The strategic use of terminal sire mating should be considered just during breeding season, or the use of alternative sire breeds should be evaluated.

Host Genetics of Response to Porcine Reproductive and Respiratory Syndrome in Sows: Antibody Response as an Indicator Trait for Improved Reproductive Performance.

Antibody response to porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) infection, measured as sample-to-positive (S/P) ratio, has been proposed as an indicator trait for improved reproductive performance during a PRRS outbreak in Landrace sows. However, this result has not yet been validated in Landrace sows or evaluated in terminal sire lines. The main objectives of this work were to validate the use of S/P ratio as an indicator trait to select pigs during a PRRS outbreak and to explore the genetic basis of antibody response to PRRSV. Farrowing data included 2,546 and 2,522 litters from 894 Duroc and 813 Landrace sows, respectively, split into pre-PRRS, PRRS, and post-PRRS phases. Blood samples were taken from 1,231 purebred sows (541 Landrace and 690 Duroc) following a PRRS outbreak for subsequent PRRSV ELISA analysis for S/P ratio measurement. All animals had high-density genotype data available (29,799 single nucleotide polymorphisms; SNPs). Genetic parameters and genome-wide association studies (GWAS) for S/P ratio were performed for each breed separately. Heritability estimates (± standard error) of S/P ratio during the PRRS outbreak were moderate, with 0.35 ± 0.08 for Duroc and 0.34 ± 0.09 for Landrace. During the PRRS outbreak, favorable genetic correlations of S/P ratio with the number of piglets born alive (0.61 ± 0.34), number of piglets born dead (−0.33 ± 0.32), and number of stillborn piglets (−0.27 ± 0.31) were observed for Landrace sows. For Duroc, the GWAS identified a major quantitative trait locus (QTL) on chromosome (Chr) 7 (24-15 megabases; Mb) explaining 15% of the total genetic variance accounted for by markers (TGVM), and another one on Chr 8 (25 Mb) explaining 2.4% of TGVM. For Landrace, QTL on Chr 7 (24–25 Mb) and Chr 7 (108–109 Mb), explaining 31% and 2.2% of TGVM, respectively, were identified. Some of the SNPs identified in these regions for S/P ratio were associated with reproductive performance but not during the PRRS outbreak. Genomic prediction accuracies for S/P ratio were moderate to high for the within-breed analysis. For the between-breed analysis, these were overall low. These results further support the use of S/P ratio as an indicator trait for improved reproductive performance during a PRRS outbreak in Landrace sows.

High Heritabilities for Antibiotic Usage Show Potential to Breed for Disease Resistance in Finishing Pigs.

The use of antimicrobials in animal production is under public debate, mainly due to the risk of transfer of resistance to pathogenic bacteria in humans. Therefore, measures have been taken during the last few decades to reduce antibiotic usage in animals, for instance, by national monitoring programmes and by improving animal health management. Although some initiatives exist in molecular genetic selection, quantitative genetic selection of animals towards decreased antibiotic usage is an underexplored area to reduce antibiotic usage. However, this strategy could yield cumulative effects. In this study, we derived new phenotypes from on-farm parenteral antibiotic records from commercially grown crossbred finishing pigs used in the progeny test of Piétrain terminal sires to investigate the heritability of antibiotics usage. Parenteral antibiotic records, production parameters and pedigree records of 2238 full-sib pens from two experimental farms in Belgium between 2014 and 2020 were analysed. Heritability estimates were moderate (18–44%) for phenotypes derived from all antibiotic treatments, and low (1–15%) for phenotypes derived from treatments against respiratory diseases only. Moreover, genetic correlations between these new phenotypes and mortality were low to moderate (0.08–0.60) and no strong adverse genetic correlations with production traits were found. The high heritabilities and favourable genetic correlations suggest these new phenotypes, derived from on-farm antibiotics records, to be promising for inclusion in future pig breeding programs to breed for a decrease in antibiotics usage.

Genetic analyses of novel traits derived from CT scanning for implementation in terminal sire sheep breeding programmes

This study used archived CT scanning images from Texel (n = 3534), Suffolk (n = 2357) and Charollais (n = 2013) ram lambs, scanned between 1997 and 2016 as part of the national UK terminal sire breeding programmes, to measure new, previously unexploited, CT phenotypes for product quality. The new CT phenotypes included 12 traits relating to eye muscle dimensions, spine region lengths and vertebrae numbers, and intramuscular fat (IMF), as a predictor of meat quality. The aim was to estimate genetic parameters for these new traits, confirm genetic parameters for existing growth and carcass traits, and investigate relationships amongst traits, when adjusted for either age or live weight. The new CT traits were generally moderately heritable (h2 ranging from 0.23-0.54 when adjusted for age) within each breed. Notable exceptions were: vertebrae counts, which had lower heritabilities (0.11-0.18) in the Suffolk and Texel; lumbar region spine length and vertebrae count in the Charollais, (0.04); and CT-predicted IMF in the Charollais (0.88). Generally, genetic variation decreased, but heritabilities increased, when traits were adjusted for live-weight rather than age, ranging from h2 0.21-0.74 for the new CT traits, except for the Charollias lumbar spine length (0.01) and CT-predicted IMF (0.87). Within-breed genetic correlations between new CT traits and current CT traits (carcass fat and muscle weights, muscularity), ultrasound tissue depths, or scan weight (at ~21 weeks), were low to moderate. High genetic correlations were observed between ultrasound and CT measured eye muscle depth (r = 0.77-0.85). Genetic correlations between CT-predicted IMF and total carcass fat estimates, however, were unfavourable (large and positive; r = 0.66-0.96), especially in the Suffolk and Charollais, suggesting little scope for divergent selection between fat depots. Some unfavourable genetic correlations of spine length with CT muscle weight or eye muscle depth were also estimated, after live weight adjustment. Possibilities therefore exist for genetic selection on additional product quality traits that can be routinely measured by CT scanning. Adjusting new and existing carcass traits for live weight, rather than age, should increase heritabilities and provide a more relevant industry end-point. These findings could contribute to the production of a new selection index, with optimal weightings on growth, carcass and product quality traits, for a sustainable UK terminal sire sheep breeding programme.

114 What Is the Impact of Dairy Influence Cattle on the Traditional Beef Industry Structure?

Abstract The U.S. cow inventory includes approximately 31 million beef cows and 9 million dairy cows, so flow of cattle from dairies into beef production influences the traditional beef industry structure. Dairy-influenced cattle have historically entered the beef supply chain as cull cows and calf-fed Holstein steers. Culled dairy cows account for approximately half of the cows harvested in the United States annually. Fed steers and heifers of dairy influence are estimated to account for 15% of annual steer and heifer slaughter. Advancements in data availability, genomics, and reproductive technologies have enabled more precise selection of dairy replacement heifers and more pregnancies to be allocated to a terminal sire. Recently, the use of beef semen to breed dairy cows that are not desirable for producing replacement heifers has become more widespread. Beef-on-dairy calves are often moved to calf ranches shortly after birth where they are weaned and grown before transitioning to traditional grow yards or feedlots. In comparison to traditional range beef production, calves of dairy origin are weaned at a younger age, have more restricted mobility early in life, and are fed a delivered ration for a greater number of days. While carcasses of dairy-originated fed cattle excel in subcutaneous leanness and marbling, calves originating from dairies typically experience greater morbidity, poorer feed conversion, and poorer dressed yields compared to native fed cattle. Future opportunities to optimize beef production from the dairy herd include refining sire selection to consistently produce high quality calves, reducing variation in calfhood management, and identifying optimal nutrition and growth technology programs for calves from dairies.

127 Antibody Response as an Indicator Trait for Improved Reproductive Performance During a PRRSV Outbreak: Genetic Correlations of S/P Ratio with Reproductive Traits in Landrace and Duroc Sows

Abstract Previous studies proposed the use of antibody response to Porcine Reproductive and Respiratory Syndrome virus (PRRSV), measured as sample-to-positive (S/P) ratio, as a potential indicator trait to improve the reproductive performance of PRRSV-infected Landrace sows. However, this indicator trait has not yet been validated in Landrace sows or evaluated in a terminal sire line, such as Duroc. The main objective of this work was to perform host-genetic analyses of S/P ratio and reproductive traits during a PRRSV outbreak in maternal and terminal breeds. The data consisted of 690 Duroc and 541 Landrace multiparous sows (1.9±1.2 and 2.3±1.5, respectively) with S/P ratio collected at approximately 54 days after the predicted beginning of the outbreak. Of these, 644 Duroc and 528 Landrace sows also had reproductive data recorded during the PRRSV outbreak comprising number of piglets born alive (NBA), stillborn piglets (NSB), mummified piglets (NBM), number born dead (NBD; sum of NSB and NBM), total number born (TNB; sum of NBA and NBD), and number weaned (NW). All animals had genotype data on ~30K SNPs common across both breeds. Heritability estimates (± standard error) of S/P ratio during the PRRSV outbreak were moderate, with 0.33±0.06 for Duroc and 0.28±0.07 for Landrace. Reproductive traits during the PRRSV outbreak had overall low heritability estimates (≤0.18). Favorable genetic correlations of S/P ratio with NBA (0.65±0.33), in accordance with previous studies, and NBD (-0.33±0.28) were observed for Landrace sows only. Estimates of genetic correlation with other traits were -0.21±0.30 (NBM), -0.12±0.29 (NSB), 0.10±0.38 (NW), and 0.54±1.29 (TNB) for Landrace. For Duroc, these estimates were weaker: -0.33±0.40 (NBA), 0.26±0.27 (NBA), and 0.28±0.30 (NW), with convergence issues for mortality traits. These results further support the use of S/P ratio as an indicator trait for improved reproductive performance during a PRRSV outbreak in Landrace sows.

Effect of terminal sire line and timing second vaccination on effectiveness of immunocastration, performance, and carcass and meat quality

Performance (from 10 weeks until slaughter), carcass and meat quality, and effectiveness of immunocastration was compared in crossbred offspring of stress positive (BP+) and negative (BP-) Belgian Piétrain and Canadian Duroc (CD) given the second vaccination of Improvac® at different times (4, 6, 8 weeks before slaughter). CD offspring had a significantly higher daily gain (DG) and feed intake (DFI), and lower predicted lean meat percentage (LMP) and dressing yield compared to BP+ and BP-, while feed conversion ratio (FCR) did not differ. CD offspring had significantly lower drip loss and higher pHi, intramuscular fat content than BP+ and BP- (except for pHi). No significant effect of vaccination time on DG nor FCR was observed. Predicted LMP tended to increase as time-post injection decreased, while meat quality was minor affected. Earlier vaccination had no effect on the effectiveness of immunocastration based on testosterone and GnRH-binding.

Influence of Immunocastration on Slaughter Traits and Boar Taint Compounds in Pigs Originating from Three Different Terminal Sire Lines.

Simple SummaryDue to the negative public opinion and welfare issues related to surgical castration, gradual introduction of alternatives like entire males and immunocastrates is taking place. Despite several economical and welfare advantages that the alternatives offer, numerous issues (i.e., boar taint, meat quality alterations), as well as their interactions with rearing and breeding (genetic) factors remain unanswered. Therefore, the focus of this study was to investigate the possibility of using different commercial sire lines in three male sex categories (entire males, immunocastrates, surgical castrates) and to compare their carcass traits, meat quality and boar taint compounds. A significant effect of terminal sire line and/or male category together with their interaction was observed for most of the investigated carcass and meat quality traits. The observed interaction should be taken into consideration when deciding on the production of a specific male category.The aim of the research was to investigate the influence of terminal sire line (TSL) and male category (MC) on carcass and meat quality of commercial fatteners. The study was performed on 180 pigs originating from three terminal sire lines: A (Pietrain × Large White), B (pure Pietrain), and C (Pietrain × Duroc × Large White), being assigned to three groups according to MC: immunocastrates (IC, n = 60), surgical castrates (SC, n = 60) and entire males (EM, n = 60). TSL affected most of the carcass and meat quality traits, together with the androstenone concentration. At the same time, MC had a significant effect on fat thickness, ham circumference, drip loss, cooking loss and androstenone and skatole concentrations. A significant interaction effect was observed for carcass length and ham circumference, as well as for most of the measured meat quality traits (except cooking loss, CIE L*, CIE b*, and Warner Bratzler Shear Force (WBSF)). Among the three investigated sire lines, immunocastration was shown to be most beneficial for fatteners sired by the TSL C. However, if deciding to raise EM, fatteners from the TSL B are recommended in terms of carcass and meat quality, although strategies for avoiding boar taint in their carcasses must be taken into consideration.

Single-step genomic evaluation of lambing ease in Australian terminal sire breed sheep

Context Australian sheep breeding values (ASBVs) for the categorical trait of lambing ease are routinely estimated by Sheep Genetics via a threshold model. This has been pedigree-only, and has not utilised genomic information. Aim The present study aimed to update the genetic evaluation model and parameters for lambing ease for terminal sire sheep (dominated by White Suffolk and Poll Dorset breeds). The model includes correlations with birthweight and gestation length. Cross-validation was used to determine the value of the improved models and the inclusion of genomic information. Methods New data-preparation pipelines were developed to accommodate improved data-filtering methods and contemporary group construction. Genetic parameters, including correlations among traits, were estimated using continuous and threshold models, with various combinations of effects in mixed animal models. Cross-validation of breeding values was performed against progeny performance, by using forward prediction. Key results The increased volume of data, improved data preparation steps and enhanced evaluation software now allow a more complex model to be fitted, including maternal, sire by flock-year and genetic group effects, which were significant for all traits, along with the inclusion of multiple sire groups in the pedigree. However, the inclusion of the direct-maternal covariance and sire by flock-year terms resulted in unrealistically inflated estimates of some components, and thus the final covariance matrices required some adjustments. Cross-validation of breeding values was performed against progeny performance using forward prediction. For all traits, the phenotype accuracies and estimated breeding value correlations were higher from the new model without genomics than were those from the current routine evaluation. The benefit from including genomic information based on cross-validation is minimal currently but is expected to improve as the size of the reference population grows. Further work is required to define acceptable data-quality thresholds for the construction of datasets for routine breeding value estimation. Conclusions The new model and parameters resulted in ASBVs with an improved predictive ability, with increased accuracy and reduced bias compared with the current analysis. Furthermore, a small increase in accuracy was observed for all traits from utilising genomic information in the model. Implications The new genetic evaluation procedures and models will be used to update those being applied in the routine Sheep Genetics evaluation system and also support further index development for the terminal sire breeds in Australia.

Vitality in relation to litter size of crossbred pigs and the effect of the terminal sire line

Context Most research on sire lines is linked to growth and carcass traits. Only a limited number of field trials explore the effect of sire line on piglet vitality, litter size and the interactions between these traits. Aim The aim of this study was to examine the effect of sire line on the growth performance and vitality of progeny from birth to weaning and to evaluate the lines with respect to their impact on litter size. Methods Data included 150 litters of a Synthetic sire line (A) and 154 of a Piétrain sire line (B), with 4209 piglets born alive, which resulted from matings to 337 dams (Camborough PIC). The numbers of total born and born alive piglets per litter were recorded. Within 24 h after birth, piglet individual birthweight (BWbirth), sex (male/female) and body temperature (BT) were also recorded. At weaning, mortality rates and weaned pigs per sow were registered. At the day of weaning, 665 randomly chosen pigs were individually weighed. Weaning weights (WW) were used to calculate the weaning average daily gain (WADG). Key results Sire line significantly affected number of total born (P &lt; 0.0001), number born alive (P &lt; 0.01) and number of weaned pigs per sow (P &lt; 0.01). Across lines, each additional piglet per litter resulted in a 31.2 g decline in BWbirth (P &lt; 0.001). Larger litter sizes, higher BWbirth (P &lt; 0.01) and piglets with a lower BT (P &lt; 0.0001) were detected in litters of Sire line B compared with litters of Sire line A. No differences between lines were detected for WADG, WW and pre-weaning mortality (P &gt; 0.05). A positive correlation between birthweight and WW resulted in a correspondingly higher WADG (P &lt; 0.0001). Overall, heavier BWbirth piglets had a higher BT (P &lt; 0.0001). Conclusions The present study indicates that Sire line B would offer a possibility to maintain litter size at a high level and, simultaneously, achieve higher BWbirth, with consequently more vital piglets. Implication It is important to emphasise that further selection for litter size in dam lines is not indicated in terms of animal welfare but also production efficiency. Instead, it seems feasible to follow the above strategy and stabilise litter size at a high level, while at the same time breeding for vitality and survivability in sire lines.

Utilising dual-purpose crops to produce prime lambs: comparison of White Dorper and Merino sheep on crops and pasture

Context Dual-purpose crops (for grazing and grain) are an important part of the feedbase in mixed farming systems in the medium-rainfall zone of southern Australia. On these farms, non-wool sheep breeds such as the Dorper may provide an opportunity to increase lamb production while reducing labour costs compared with traditional sheep breeds. Aims This study was designed to compare lamb production systems based on White Dorper and Merino ewes joined to a terminal sire, while exploiting a feedbase that included dual-purpose crops. Methods Two experiments were conducted at Wagga Wagga, New South Wales, during 2013 (Expt 1) and 2014 (Expt 2). In February in both experiments, White Dorper ewes were joined to either White Dorper or White Suffolk rams (lambs designated DD and WSD, respectively), and Merino ewes were joined to White Suffolk rams (lambs designated WSM). In Expt 1 a dual-purpose wheat (Triticum aestivum L.) crop was established and the paddock subdivided into nine plots (0.93 ha each). Pregnant ewes were allocated to plots on the basis of genotype (DD, WSD or WSM grazing separate plots) after blocking for number of fetuses identified at mid-pregnancy scanning, with three replicates based on genotype. Lambing commenced on 28 June, and ewes grazed the crop from 27 June to 14 August and then continued to graze in the same groups on a lucerne (Medicago sativa L.)–clover (Trifolium spp.) pasture subdivided into nine plots (2.1 ha), maintaining the same replicates until weaning on 2 October. In Expt 2, the cropping paddock was subdivided into six plots (1.86 ha each) sown to either dual-purpose wheat or canola (Brassica napus L.), with three replicates. Lambing commenced on 13 July. Merino and White Dorper ewes grazed the crops concurrently from 19 June to 12 August, and then lucerne–clover pasture until weaning on 29 September. In both experiments a mineral supplement was fed to ewes grazing wheat during the crop-grazing period. Key results Feed on offer was low (0.33 t/ha) in dual-purpose wheat crops at the start of grazing in Expt 1 and did not differ among genotypes at the cessation of grazing crops. Feed on offer was higher in wheat than canola at the commencement of grazing in Expt 2 (2.6 vs 2.3 t/ha; P = 0.009), and a higher stocking rate was maintained on wheat than canola from the start of lambing. White Dorper ewes maintained a higher body condition score than Merino ewes throughout both experiments. In Expt 2, some ewes had serum magnesium and calcium levels below the normal range, and a high number of ewes (20%) required assistance at lambing. Number of lambs weaned per ewe scanned pregnant was similar among genotypes in both experiments. WSD lambs were heaviest (P &lt; 0.05) at weaning and DD lambs had greatest (P &lt; 0.05) fat depth over the eye muscle at weaning. Conclusions and implications When grazed on a feedbase typical of mixed farms in the medium-rainfall zone of southern NSW, White Dorper ewes were in higher body condition than Merino ewes; however, reproductive rates were similar. Joining White Dorper ewes to a terminal sire may increase weaning weight of lambs compared with joining to a White Dorper ram, or a Merino maternal system.

Comparison of performance of F1 Romanov crossbred ewes with wool and hair breeds during fall lambing and body weight and longevity through six production years.

The objective of this study was to evaluate wool (Dorset and Rambouillet) and hair (Dorper, Katahdin, and White Dorper) breeds for their ability to complement Romanov germplasm in an annual fall lambing system by estimating direct maternal grandsire and sire breed effects on economically important lamb and ewe traits. After 3 yr of evaluation under spring lambing, ewes of the five F1 types were transitioned to spring mating, exposed to composite terminal sires, and evaluated under a barn lambing system at 4, 5, and 6 yr of age. A total of 527 first generation crossbred (F1) ewes produced 1,151 litters and 2,248 lambs from 1,378 May exposures. After accounting for differences in dam age, birth type, and sex, lamb survival to weaning was unaffected by maternal grandsire breed (P = 0.30). However, lambs born to 50% Dorset (16.8 ± 0.21 kg) or 50% White Dorper ewes (16.8 ± 0.28 kg) were heavier at weaning than those born to 50% Katahdin dams (13.8 ± 0.32 kg; P < 0.001). Additionally, lambs born to 50% Dorset ewes were heavier than those born to 50% Rambouillet (16.0 ± 0.22 kg) and 50% Dorper ewes (15.7 ± 0.33; P ≤ 0.03), but no other pairwise maternal grandsire breed differences were observed (P ≥ 0.06). Ewe body weight (n = 3,629) was recorded prior to each of six possible mating seasons and, across ages, was greatest for Dorset- and Rambouillet-sired ewes (56.7 ± 0.44 and 56.5 ± 0.45 kg, respectively), intermediate for Dorper- and White Dorper-sired ewes (54.7 ± 0.78 and 54.1 ± 0.64 kg, respectively), and least for Katahdin-sired ewes (51.5 ± 0.45 kg). Fertility after spring mating (0.80 ± 0.03 to 0.87 ± 0.02), litter size at birth (1.46 ± 0.09 to 1.71 ± 0.07), and litter size at weaning (1.25 ± 0.06 to 1.46 ± 0.06) were not impacted by sire breed (P ≥ 0.16). Ewe longevity, assessed as the probability of being present after 6 production years, was also not affected by sire breed (0.39 ± 0.03 to 0.47 ± 0.03; P = 0.44). Rambouillet-sired ewes weaned more total weight of lamb (21.5 ± 0.94 kg) than Katahdin-sired ewes (17.8 ± 0.94 kg; P = 0.05), but no other sire breed differences were detected (P ≥ 0.07). Results demonstrated that incorporating the Romanov into a crossbreeding system is a practical means of improving out-of-season ewe productivity.

Survivability of pure and cross bred chickens at early and late growth phases in Nigeria humid tropics

Survival is a general measure of an animal's fitness. In commercial poultry production, mortality can result from a range of conditions (disease, physiological stress, environmental condition and aggressive behaviour. This study was aimed at evaluating Yoruba Ecotype Chicken (YEC), Sussex (SS), Goliath (GG), Marshall (MM) and their crossbred offspring for survivability in the Nigeria humid tropical climate. A total of 529chicks were raised fromday-old to 8 weeks (early growth phase) and 9 weeks to 20 weeks of age (Late growth phase). Data obtained were subjected to the Kaplan meier survivability test using SPSS (2012) version 21. The findings of the study revealed that at early growth phase, pure bred YEC x YEC had highest survivabilityof 91.20% while crossbred YEC x GG had the least survivability rate of 75.00%. The overall survivability of 86.40% was recorded at this stage. Late growth phase recorded highest survivability (100%) for cross bred YEC x GG while cross bred YEC x MM had the least survivability of 87.50% while the overall survivability was 94.10%. This study concluded that YEC are hardy compared with other genotypes, especially at the early growth phase while cross breeding improved the performance of YEC x GG at the late growth phase. The study recommends that YEC should be used as terminal sire in crosses involving exotic breeds for proper adaptability and performance in the Nigeria humid tropics.

Comparison of performance of F1 Romanov crossbred ewes with wool and hair breeds during spring lambing under intensive and extensive production systems.

The objective was to evaluate wool (Dorset and Rambouillet) and hair (Dorper, Katahdin, and White Dorper) breeds for their ability to complement Romanov germplasm in two distinct production systems by estimating direct sire and grandsire effects on lamb growth, survival, and ewe productivity traits. Rams of the five breeds (n = 75) were mated to Romanov ewes (n = 459) over a 3-yr period to produce five types of crossbred lambs (n = 2,739). Sire breed (P > 0.06) did not impact body weight or survival traits of the first-generation crossbred (F1) lambs. The productivity of retained crossbred ewes (n = 830) mated to Suffolk and Texel terminal sires was evaluated at 1, 2, and 3 yr of age in each production system. In the intensive production system, labor and harvested feed were provided for sheep that lambed in March in barns, and ewes were limited to rearing two lambs with additional lambs reared artificially. Ewes in the extensive production system lambed in May on pasture and were responsible for rearing all lambs born with no labor or supplemental feed provided before weaning. A total of 1,962 litters and 4,171 lambs from 2,229 exposures to two terminal sire breeds (Suffolk and Texel) were produced in the experiment. Crossbred ewes in the intensive production system were mated in October, resulting in larger litter sizes than crossbred ewes mated in December for the extensive production system. However, single- and twin-born lamb mortality was similar between the two systems that differed greatly in labor, feed, and facilities. Lambs produced in the intensive system received concentrate feed from an early age and were heavier at 24 wk of age than lambs produced in the extensive system. These outcomes resulted in greater 24-wk litter weight in the intensive than in the extensive system (P < 0.0001). Unexpectedly, the relative performance of crossbred types did not differ importantly between production systems. White Dorper × Romanov crossbred ewes had numerical advantages in productivity in each system; however, differences between ewe types were not significant. In the extensive system, without labor and shelter at lambing or supplemental feed until weaning, 3-yr-old crossbred ewes of all types averaged 1.78 lambs marketed per ewe lambing, and 40% of the ewes that gave birth to triplets weaned their entire litters. These results document that prolific sheep and extensive systems can be successfully combined if appropriate crossbred types are used.