Soladoye, P. O., Shand, P. J., Aalhus, J. L., Gariépy, C. and Juárez, M. 2015. Review: Pork belly quality, bacon properties and recent consumer trends. Can. J. Anim. Sci. 95: 325-340. Several factors can affect pork belly quality and, subsequently, bacon quality. Going by the recent trends in the bacon market and bearing in mind the more choosy nature of the consuming populace, it is imperative to consider the factors that can affect or improve bacon quality, thereby sustaining the current market surge. In as much as both genetic and environmental factors have been identified as largely affecting muscle food quality, nutritional interventions also seem to be a very viable tool to improve the quality of meat and its products. Processing and storage methods can also affect bacon quality, including microbial quality, physicochemical attributes and palatability. Both objective and subjective measures have been explored in assessing belly quality, most of which use belly softness and fatty acid profile as yardsticks, whereas bacon quality has been widely assessed only subjectively in terms of fat quality and slice integrity. Although consumers'and producers'quality perceptions seem to be in conflict, it is the responsibility of all stakeholders in the bacon industries to come together in ensuring a balanced approach to satisfy both parties along the production chain.

Miller-Cushon, E. K. and DeVries, T. J. 2015. Invited review: Development and expression of dairy calf feeding behaviour. Can. J. Anim. Sci. 95: 341-350. Feeding and housing practices for dairy calves impact performance and growth early in life, as well as feeding behaviour. There is also increasing evidence that early exposure to different feeding and housing strategies influence the development of feeding behaviour. The dairy calf needs access to milk in sufficient quantities to maintain health and high-levels of growth. In addition, intake of solid feed, such as grain concentrate, is necessary early in life to establish fermentation and develop the rumen. In dairy calves, feeding behaviour patterns can have direct impact on nutrient consumption and, consequently, growth. Further, recent research has provided evidence that behaviour patterns that develop in response to management factors early in life may persist once learned, potentially having longer-term implications for health and welfare. Thus, there is potential for various nutritional, housing, and management factors to impact the learning of feeding behaviour early in the life of dairy calves. This review provides several examples of early management factors that influence feeding behaviour of dairy calves and, in turn, impact calf growth and welfare. For example, providing continuous, ad libitum access to milk results not only in greater growth, but also in meal patterns that more closely resemble the natural behaviour of a calf suckling its dam. Housing management also has the potential to influence when, and how much, a calf eats. Whereas social facilitation promotes intake, particularly at weaning, competition for feed in group-housed calves restricts feeding patterns and degree of feeding synchrony. With regards to provision of solid feed, recent data suggest that providing physically effective hay, in addition to grain concentrate, may be beneficial for the rumen environment and consequent growth and efficiency. However, the physical form and presentation of forage may also influence feeding behaviour of calves, in particular feed sorting, which can impact both immediate nutrient intakes as well as the development and persistence of that behaviour. For example, calves provided hay and concentrate as a mixture begin to sort their feed early in life, with the pattern of sorting depending on hay particle size. Feed sorting in young calves may reflect a motivation to consume a proportion of hay in the diet. In general, it appears to be beneficial for early growth and welfare to support milk and solid feed intake through unrestricted allowances and less-competitive feeding environments. Continued research in this area is needed to assess the longevity of learned behaviour patterns, and what factors may influence their persistence.

Sadeghi-Sefidmazgi, A. and Amer, P. R. 2015. Milk losses and quality payment associated with somatic cell counts under different management systems in an arid climate. Can. J. Anim. Sci. 95: 351-360. The objectives of this research were (1) to estimate the economic benefits or new marketing opportunities due to a reduction in milk somatic cell count (SCC) for dairy producers through improved management practices and (2) to quantify the production loss associated with SCC under different management systems. A total of 38 530 average lactation SCC records for 10 216 Holstein cows gathered on 25 dairy farms from January 2009 to October 2012 in Isfahan (Iran) were analyzed under 13 types of herd management practices including 40 levels of health, milking and housing conditions. The results show that there are many well-established management practices associated with higher-quality payment for SCC that have not yet been applied in Isfahan dairy farms. The lowest and highest economic premium opportunity (US$) from SCC were estimated to be for production systems applying washable towels for teat cleaning (5.69) and production systems with no teat disinfection (31.07) per cow per lactation. Results indicate that any increase of one unit in average lactation somatic cell score is expected to cause a significant reduction in average lactation 305-d milk yield from 36.0 to 173.4 kg, depending on the level of management practices employed. In general, farmers with higher milk yield and well-managed practices for mastitis control would lose more milk when an increase occurs in SCC.

Urbanski, P., Pierzchala, M., Terman, A., Kamyczek, M., Rózycki, M., Roszczyk, A. and Czarnik, U. 2015. The relationship between the polymorphism of the porcine CAST gene and productive traits in pigs. Can. J. Anim. Sci. 95: 361-367. The aim of the study was to characterize the polymorphism of the calpastatin gene identified with ApaLI, Hpy188I and PvuII restriction enzymes in two pig breeds and one line bred in Poland, and to evaluate the relationship between the CAST genotype and carcass traits. The analysis covered a total of 617 pigs of two breeds, Polish Landrace (185) and Polish Large White (216), and synthetic line L990 (216). All animals studied appeared to be monomorphic at two loci: CAST/ApaLI and CAST/Hpy188I, while three genotypes were observed at CAST/PvuII locus. Statistical analysis was carried out for each breed separately using the least square methods of the GLM procedure. The model included the effect of the CAST genotype, fixed effect of the RYR1 genotype and the effect of the sire. Because the RYR1 genotype could significantly modify the effect of other genes, the effect of the RYR1 genotype was included in the statistical model. The relationship between the polymorphism and several productive traits was identified in each of the study groups of pigs. Animals carrying the heterozygous genotype at this locus showed most extreme values for some of the traits tested. Our results suggest that the CAST /PvuII genotype might be utilized in the selection of valuable pig carcass traits, particularly weight and size of the loin.

Manafiazar, G., Basarab, J. A., Baron, V. S., McKeown, L., Doce, R. R., Swift, M., Undi, M., Wittenberg, K. and Ominski, K. 2015. Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers. Can. J. Anim. Sci. 95: 369-381. There is limited knowledge of how cattle tested for feed efficiency under drylot conditions perform when they graze on summer pasture. Residual feed intake adjusted for end of test backfat thickness (RFI_fat) was determined on 171 beef crossbred heifers under drylot conditions over 2 yr using an automated system. Upon completion of the test, the 10 lowest and 10 highest RFI_fat (-0.54±0.17 vs. 0.58±0.15 kg DM d^-1) heifers in 2012, and the 14 lowest and 14 highest RFI_fat (-0.47±0.16 vs. 0.53±0.19 kg DM d^-1) heifers in 2013 were selected and placed on meadow bromegrass pasture to investigate the effect of RFI_fat ranking on their grass intake and performance on the pasture. The pasture adaptation period (8 d in 2012 and 19 d in 2013) was followed by a pasture feed intake experiment during which heifers were dosed twice daily (0815 and 1415) with 500 g of C₃₂-labeled feed pellet for 13 d (day 0 to 12) and fecal sampled twice daily (0815 and 1415) from day 8 to 12. Forage DM intake on pasture for each heifer was determined using the double alkane (C₃₁/C₃₂) methodology. High and low RFI_fat heifers were similar in body weight (BW), backfat and rump fat thickness, and average daily gain (ADG) during the grazing trial period, except backfat thickness at the end of test period. However, low RFI_fat heifers consumed 5.3% less forage when expressed as kg DM d^-1 (8.20±0.08 vs. 8.66±0.09, P<0.001) and 5.1% less when expressed as a percentage of body weight (1.86±0.02 vs. 1.96±0.02% of BW, P<0.001) compared with high RFI_fat heifers. RFI_fat measured under drylot conditions in growing heifers was positively correlated to grazed RFI_fat determined in pregnant heifers (r_p=0.30, P=0.04). These results suggest that beef heifers classified as low RFI_fat during the post-weaning drylot period had lower dry matter intake as heifers in their first pregnancy grazing tame pasture, with no negative impact on their body weight, back-fat thickness, and ADG compared with their high RFI_fat herdmates.

Thangavelu, G., Gobikrushanth, M., Colazo, M. G. and Ambrose, D. J. 2015. Pregnancy per artificial insemination and pregnancy loss in lactating dairy cows of a single herd following timed artificial insemination or insemination at detected estrus. Can. J. Anim. Sci. 95: 383-388. The objective of this retrospective study was to determine the factors affecting pregnancy per artificial insemination (P/AI) and pregnancy loss in lactating dairy cattle. Breeding records (n=1466) for 5 consecutive years were evaluated from one dairy herd. The effects of type of breeding [timed artificial insemination (TAI; n=1246) vs. insemination at detected estrus (IDE; n=220)], parity (primiparous vs. multiparous), body condition score (BCS; low =2.5 vs. high >2.5), year, season (summer vs. other seasons) and fertility group (high fertile <3 vs. low fertile ≥3 inseminations), on P/AI and pregnancy loss (i.e., late embryonic/early fetal loss, abortion and stillbirth) were determined using the GLIMMIX procedures of SAS software. Pregnancy per AI was influenced by type of breeding and season. Pregnancy per AI was lower (P<0.05) in cows that were TAI (28.7%) than IDE (37.1%) and during summer (30.3%) than other seasons of the year (35.5%). Pregnancy loss was higher (P<0.05) in low BCS (9.1%) than in high BCS (1.9%) cows. However, parity, year, and fertility group affected neither P/AI nor pregnancy loss.

Jiang, Y., Zhang, W., Gao, F. and Zhou, G. 2015. Effect of sodium butyrate on intestinal inflammatory response to lipopolysaccharide in broiler chickens. Can. J. Anim. Sci. 95: 389-395. The aim of this study was to investigate the effect of sodium butyrate (SB) supplementation on intestinal inflammatory response to lipopolysaccharide (LPS) in broiler chickens. A total of 120 one-day-old chickens (Arbor Acres) were divided into two groups and fed a control diet (without SB) or 1.00 g SB kg^-1 diet. Half of the chickens fed each diet were injected intra-peritoneally with 0.5 g kg^-1 body weight of Escherichia coli LPS at 16, 18 and 20 d of age. The results showed that the LPS challenge decreased (P<0.05) villus height and the ratio of villus height to crypt depth (V/C ratio), increased (P<0.01) crypt depth of the duodenum. SB supplementation increased (P<0.05) villus height, crypt depth and V/C ratio of the duodenum and jejunum, except for the crypt depth of the jejunum. The LPS challenge increased (P<0.05) myeloperoxidase (MPO) activities, intercellular adhesion molecule-1 (ICAM-1) and activated nuclear factor kappa B (NF-κB) levels in mucosa of the duodenum and jejunum, while decreasing (P<0.05) insulin-like growth factor-1 (IGF-1) concentrations. The LPS challenge increased (P<0.05) the mRNA levels of interleukin-1beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in duodenal mucosa. SB supplementation decreased (P<0.05) the MPO activities and mRNA expression of TNF-α in the duodenal mucosa, and the activated NF-κB levels in mucosa of the duodenum and jejunum. There were no significant interactions between dietary SB and LPS on the histomorphology of the small intestine and those inflammatory mediators except for MPO and ICAM-1 in duodenal mucosa (P<0.05). The results indicate that SB supplementation could improve the intestinal morphology and function of broiler chickens and partially attenuate inflammatory responses caused by LPS challenge but not involving NF-κB activation.

Carter, N. A., Dewey, C. E., Lukuyu, B., Grace, D. and de Lange, C. F. M. 2015. Nutrient composition and seasonal availability of local feedstuffs for pigs in western Kenya. Can. J. Anim. Sci. 95: 397-406. In this study, nutritional values and seasonal availability were estimated for 25 local feedstuffs for pigs in western Kenya, based on analyzed nutrient contents and a review of the literature. Characteristics considered included: crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), ether extract (EE), Ca, P, standardized total tract digestible (STTD) P, total Lys, standardized ileal digestible (SID) Lys (all as g kg^-1 of DM), and digestible energy (DE) (kcal kg^-1 DM). Contents of total Lys, SID lysine, STTD P, and DE were estimated. Overripe improved-variety avocado (Persea americana) had the greatest estimated DE (5280 kcal kg^-1 DM) and EE content (521 g kg^-1 of DM). Cattle rumen content had the greatest NDF content (664 g kg^-1 of DM). Sun-dried fish (Rastrineobola argentea) had the greatest estimated STTD P content (13.5 g kg^-1 of DM). Amaranthus spinosus L. had the greatest Ca content (26 g kg^-1 of DM). Fresh cattle blood had the greatest CP and estimated SID Lys content (944 and 83.0 g kg^-1 of DM, respectively). Feedstuffs availability periods are: March through May plus September and October; June through August; and November through February. Local feedstuffs of sufficient nutritional value for pigs are seasonally available. Estimated nutritional values may assist in diet formulation.

Salim, H., Wood, K. M., Cant, J. P. and Swanson, K. C. 2015. Influence of feeding increasing levels of dry or modified wet corn distillers' grains plus solubles in whole corn grain-based finishing diets on hepatic and renal mass, and glutathione peroxidase and urea cycle enzyme activities in finishing cattle. Can. J. Anim. Sci. 95: 407-415. Forty-two cross-bred steers (BW=357±5.8 kg) fed whole corn grain-based finishing diets were used in a completely randomized block (60, 120, or 180 d on feed) design (2×3 factorial arrangement of treatments plus control) to determine the effect of inclusion level [0 (control), 16.7, 33.3, and 50% of diet DM) and form (dry (DDGS) or modified wet (MWDGS)] of distillers' grains plus solubles (DGS) on hepatic and renal glutathione peroxidase (GPx) and hepatic urea cycle enzyme activities. Kidney weight (g kg^-1 of BW) increased linearly (P=0.004) with increasing inclusion levels of DGS. There were no effects (P≥0.11) of dietary treatment on hepatic and renal GPx activity (U g^-1, U mg^-1 of protein, and kU liver^-1). Hepatic carbamoyl phosphate synthetase activity (kU liver^-1 and U kg^-1 of BW) tended to linearly increase (P=0.09 and P=0.10, respectively) with increasing inclusion level of DGS. Hepatic ornithine transcarbamoylase and argininosuccinate synthetase activity (kU liver^-1 and U kg^-1 of BW) increased linearly (P≤0.05) with increasing inclusion levels of DGS. These data indicate that steers adapt to feeding up to 50% DGS by increasing kidney mass and activity of urea cycle enzymes in liver to allow for clearance of excess nitrogen. Also, hepatic and renal GPx activity, as an indicator of Se status, is not affected when typical finishing diets are fed.

Refat, B., Anele, U., He, Z. X., Bassiony, S. M., Abdel-Rahman, G. A. and Yang, W. Z. 2015. Effect of sainfoin hay and pomegranate peel extracts on in vitro fermentation and protein degradation using the RUSITEC technique. Can. J. Anim. Sci. 95: 417-423. The objectives of this study were to determine the effect of supplementation of sainfoin hay extract (SHE) and pomegranate peel extract (PPE) on in vitro rumen fermentation characteristics, protein metabolism and nutrient digestibility using rumen simulation technique (RUSITEC). The experiment was a completely randomized design with three treatments and four replications. Dietary treatments were: (1) control (10% barley silage and 90% concentrate), and control supplemented (2) with SHE (4.1 g catechin equivalent kg^-1 dry matter; DM) or (3) with PPE (2.8 g tannic acid equivalents kg^-1 DM). The experiment consisted of 10 d of adaptation and 7 d of data collection. Concentration of total volatile fatty acid (VFA) was lower (P<0.02), but molar proportion of acetate was higher (P<0.01) with SHE or PPE than control. Branched-chain VFA decreased (P<0.01) with PPE supplementation compared with control. Concentrations of large and small peptides were not affected but ammonia nitrogen (NH₃-N) concentration decreased (P<0.01) with PPE supplementation. Digestibility of DM, starch and crude protein decreased (P<0.02) with SHE and PPE supplementation compared with control. Bacterial nitrogen production (mg d^-1) and bacterial efficiency (g bacterial nitrogen kg^-1 digested organic matter) were not affected by SHE or PPE supplementation. Overall, there were no differences in VFA concentrations, nitrogen fractions and nutrient digestibility between SHE and PPE except for the concentrations of branched-chain VFA and NH₃-N, which were higher (P<0.01) with SHE versus PPE supplementation. In conclusion, supplementation of high-grain diet with SHE or PPE can decrease rumen by-pass protein; however, suppression of feed fermentation may decrease the feeding value of high-grain diet.

Kouazounde, J. B., Gbenou, J. D., He, M., Jardim, T., Jin, L., Wang, Y., Beauchemin, K. A. and McAllister, T. A. 2015. Effects of essential oils from African basil on fermentation of Andropogon gayanus grass in the Artificial Rumen (RUSITEC). Can. J. Anim. Sci. 95: 425-431. Essential oils (EO) from African basil (Ocimum gratissimum) have shown the potential to modify rumen microbial fermentation and reduce ruminal methane production from grass forages in in vitro batch cultures. However, it is not known whether the effects of EO on rumen microbial fermentation attenuate over time. The objective of this study was to examine the effects of African basil EO at 0 (control), 100, 200 and 400 mg L^-1 incubation medium on microbial fermentation and methane production in the Rumen Simulation Technique (RUSITEC) using Andropogon gayanus grass as a substrate. African basil EO quadratically affected (P<0.05) methane production gas production and the pH of fermenter liquid. Total volatile fatty acid (VFA) production was linearly decreased (P<0.05) by African basil EO along with a shift in VFA profile towards less propionate and more acetate and butyrate. African basil EO quadratically altered (P<0.05) apparent dry matter, neutral detergent fiber digestibility, ¹⁵N incorporation into total microbial protein and the total production of microbial protein. This study confirms that EO from African basil quadratically affected methane emissions arising from the ruminal fermentation of A. gayanus grass mainly by reducing overall digestibility of the forage.

Khazanehei, H., Li, S., Khafipour, E. and Plaizier, J. C. 2015. Effects of dry period management on milk production, dry matter intake, and energy balance of dairy cows. Can. J. Anim. Sci. 95: 433-444. Effects of dry-period management on milk production, feed intake, and energy balance were determined in 11 second-parity (PAR 2) and 15 third or later parity (PAR 3 ) cows. Cows were paired based on expected calving date, and randomly assigned to treatments including a conventional 60-d dry period with a 39-d far-off and a 21-d close-up diet (CONV), and a short 40-d dry period with only a close-up diet (SHORT). Treatment did not affect dry matter intake (DMI) and energy balance across the 6 wk before calving and the 4 wk after calving. Across the first 16 wk of lactation, cows on the short treatment had lower milk yield compared to cows on the CONU treatment that was mostly due to the lower production in PAR 3 cows. Also, PAR 3 cows on the SHORT treatment had lower milk protein yields and higher somatic cell counts than the other cows. In general, PAR 2 cows on the SHORT treatment had similar DMI, fat corrected milk yields, and protein and fat yields and percentages compared to cows in both parity groups on the CONV treatment. This suggests that the SHORT treatment may be suitable for PAR 2 cows, but not for older cows.

Khazanehei, H., Li, S., Khafipour, E. and Plaizier, J. C. 2015. Effects of dry period management and parity on rumen fermentation, blood metabolites, and liver triacylglyceride in dairy cows. Can. J. Anim. Sci. 95: 445-453. The effects of dry period management on rumen fermentation, blood metabolites and liver triacylglyceride (TAG) were determined in 11 second-parity (PAR 2) and 15 third-parity and older (PAR 3 ) cows. Cows were paired and randomly assigned to two treatments: (1) a short 40-d dry period (SHORT) with only a close-up diet [1.43 Mcal kg^-1 dry matter (DM)], or (2) a conventional 60-d dry period (CONV) with 39 d far-off diet (1.28 Mcal kg^-1 DM) and 21 d close-up diet (1.43 Mcal kg^-1 DM) in a randomized block design. Concentrations of total volatile fatty acids, ammonia, and lactate in rumen fluid, and also concentrations of lactate, beta hydroxybutyric acid (BHBA), urea and insulin in plasma were not affected by treatment. Across the 3 wk after calving, cows on the SHORT treatment had higher blood non-esterified fatty acid (NEFA) and glucose, and at 1 wk after calving, these cows had a higher liver TAG than cows on the CONV treatment. Also, during this time, PAR 3 cows had higher serum NEFA compared with PAR 2 cows. Results suggest that the SHORT treatment resulted in more lipolysis, TAG accumulation in the liver and glucose sparing in early lactation compared with the CONV treatment, and that this effect was greater in PAR 3 cows than in PAR 2 cows.

Kononoff, P. J., Defoor, P. J., Engler, M. J., Swingle, R. S., James, S. Y., Deobald, H. M., Deobald, R. L., Woronuk, G. N. and Marquess, F. L. S. 2015. Performance and carcass characteristics when sorting feedlot cattle on the basis of phenotype, and leptin genotype along with differential use of β-adrenergic agonists. Can. J. Anim. Sci. 95: 455-463. Crossbred steers were used in a randomized complete block design to evaluate a feedlot cattle sorting system. The sorting system combined information on live body weight, ultrasound fat thickness, coat color, and genotype on the leptin R25C genotype. Using described sorting criteria, a total of four groups (Groups 1-4) of cattle were created along with a randomly selected unsorted control (Group 5), with Groups 1 through 5 representing experimental treatments, and placed in one of five pens within each block. Block was replicated 10 times thus n equaled 50. All cattle were administered zilpaterol hydrochloride except Group 3, which we hypothesized would have a greater proportion of cattle reaching a higher value Quality Grade, and as a result administered ractopamine hydrochloride. The initial body weight of cattle was similar (P=0.426) between the control Group and Groups 1-4. Initial fat, as measured by ultrasound, was also observed to be similar (P=0.256) between these two groups. Overall, when cattle included in Groups 1-4 were compared with Group 5, hot carcass weight was greater (P=0.040), while the proportion of excessively heavy weight carcasses was less (P=0.049). Additionally, hot carcass weight gain tended (P=0.096) to be higher for Groups 1-4 compared with Group 5. No differences (P≥0.129) were observed for calculated yield grade. On average, cattle included in the Sorting Groups 1-4 returned $23 more per head than those in Group 5.

Mehdi, Y., Clinquart, A., Hornick, J.-L., Cabaraux, J.-F., Istasse, L. and Dufrasne, I. 2015. Meat composition and quality of young growing Belgian Blue bulls offered a fattening diet with selenium enriched cereals. Can. J. Anim. Sci. 95: 465-473. The objective of this study was to evaluate the effects of selenium (Se) enrichment of cereals on the performance of Belgian Blue bulls, meat quality and chemical composition. Twenty-three bulls were used in the present study. Twelve bulls were offered a control diet containing Se at a basal concentration of 58 µg kg^-1 of dry matter (DM) and the other 11 bulls were given a diet containing 173 µg kg^-1 DM of Se by means of Se-enriched spelt and barley. The Se enrichment of the diet did not affect the growth performance, the slaughter data or meat quality (P > 0.05). There were no effects of Se on tenderness, oxidative rancidity and water losses. However, there were some effects of Se enrichment on the meat chemical composition. The ether extract was decreased from 2.1 to 1.7% DM (P<0.05). There was also significant Se enrichment (P<0.001) in the longissimus thoracis muscle (177 vs. 477 ng g^-1 DM) and organs: liver (474 vs. 1126 ng g^-1 DM) and kidney (4956 vs. 5655 ng g^-1 DM), Under such conditions, the human consumption of a piece of such meat or liver can provide a large part of the recommended daily Se intake, estimated between 30 and 57%.

Khakbazan, M., Durunna, O. N., Sirski, T. K., Brewin, D. G., Huang, J., Berry, N., Iwaasa, A. D., Scott, S. L., Robins, C. D., Block, H. C. and Lardner, H. A. 2015. The effects of spring versus summer calving on beef cattle economic performance in western Canada. Can. J. Anim. Sci. 95: 475-486. The choice of calving date influences the net revenue of a calving operation as it affects the number of days that calves spend in each feeding phase and when they are subsequently marketed. These two factors determine the costs, revenue, and risk (variance) of each calving system for the calving phase of a beef system. The majority of cow-calf producers in western Canada have adopted early calving (EC) in spring due to management factors. However, late calving (LC) in the summer is an alternative beef calving system associated with higher returns due to lower system costs and higher beef prices. It may offer a better match between cow nutritional requirements and pasture availability. The objective of this study was to compare the revenues and risks for a traditional EC system and an alternative LC system at three sites in western Canada. Biological and economic data from three field experimental sites in western Canada (Brandon Research Centre in Manitoba, Western Beef Development Centre in Lanigan, Saskatchewan and Semi-Arid Prairie Agriculture Research Centre in Swift Current, Saskatchewan) were used to determine the costs and benefits of the alternative beef calving system. The results showed that even though the EC has higher cost than the LC, the EC is slightly better than LC in terms of higher net revenue potential, but it comes at a greater risk due to higher revenue variances. The EC system is usually more preferable for risk-neutral producers, whereas the LC system is more preferable for risk-averse producers.

He, M., Liang, X., Wang, K., Pu, H., Hu, Y., Ye, G., Li, X. and Liu, L. 2015. Age-related development and histomorphological observation of bursa of Fabricius in yellow quails. Can. J. Anim. Sci. 95: 487-491. The purpose of this study was to observe the age-related development and histomorphological changes in the bursa of Fabricius (BF) in Chinese yellow quails. One hundred and twenty Chinese yellow quails were divided into 12 groups. After dissecting, the weight, length, width and index analysis of the BF were determined, and histomorphological observation was performed using hematoxylin and eosin (HE) staining at different ages. The weight of the BF gradually increased with age from 0 to 5 wk, reached a peak at 5 wk (100.23±6.47), then decreased quickly from 5 to 9 wk (63.21±3.90) and decreased slowly after 9 wk (P<0.05). The length of the BF was greater at 5 wk old than at 0 wk old (11.00±2.45 vs. 5.00±1.15, P<0.05), and there was no significant difference after 5 wk of age (P>0.05). The width of the BF was similar to the length. The organ index was higher at 1 wk of age compared with 5 wk of age (1.25±0.11 vs. 0.71±0.05, P<0.05) and reached its maximum from 0 to 36 wk of age. Histomorphological analysis revealed the different development stages of the BF at different ages. We detected the age-related development of the BF in Chinese yellow quails and observed the histomorphological modifications. This study may help increase our understanding of the quail's immune system and provide a basis for immunization research in Chinese yellow quails.