Lactational performance for improving postweaning reproductive performance and lifetime performance on swine commercial farms

We studied the associations of the weaning litter weight (WLWt) and number of pigs weaned (PW) with measurements of postweaning reproductive performance and examined the repeatability of WLWt, PW and average pig weight at weaning (PIGWt) on commercial swine farms. This study spanned 6 years and was conducted using 57,611 weaning records from 11,574 sows born in 1999 on 92 farms. Variance components analysis was used to determine the repeatability of measurements of lactational performance. Mixed-effects models were used to analyze the associations of measurements of lactational performance with farrowing rate and weaning-to-first-mating interval. The values for repeatability of WLWt, PIGWt and PW were 0.31, 0.34 and 0.17, respectively. No differences in weaning-to-first-mating intervals were found among the five PW groups (< or = 6, 7 to 8, 9 to 10, 11 and 12 to 14 pigs) or among the three WLWt groups (< or = 48.0, 48.0 to 69.0 and > or = 69.0 kg). Sows with 12 to 14 PW had farrowing rates similar to those with 9 to 11 PW. Sows with a WLWt > or = 69.0 kg had the highest farrowing rate (P<0.01). However, sows with 11 PW had an approximately 100 to 200 g lighter PIGWt than those with 4 to 10 PW (P<0.01). This study suggests that increased WLWt and PW do not impair postweaning reproductive performance, but instead decrease PIGWt.     

微囊丁酸钠对母猪生产性能与仔猪生长性能的影响

40头妊娠85 d健康二元杂交经产母猪(胎次、体况、前胎产仔数一致),随机分为2组,每组20个重复,每个重复1头,分别为对照组(基础日粮)、处理组(妊娠期:基础日粮+800 g/t微囊丁酸钠;哺乳期:基础日粮+500 g/t微囊丁酸钠)。结果表明,饲粮中添加微囊丁酸钠能够显著提高母猪生产后期采食量(4.56%),显著降低母猪哺乳期的体失重(P<0.05),提高仔猪断奶日增重(P<0.05)和断奶体重。此外,处理组弱仔率较对照组下降35.72%,窝断奶仔猪数和断奶仔猪均重有上升趋势(P=0.07,P=0.14)。由此可见,微囊丁酸钠可改善母猪生产性能,提高仔猪平均日增重。     

复合微生态制剂对母黑豚繁殖性能、泌乳性能及仔黑豚生长性能的影响

试验通过研究复合微生态制剂对母黑豚繁殖性能、泌乳性能及仔黑豚生长性能的影响,以期为复合微生态制剂在黑豚养殖生产中的推广应用奠定基础。试验采用单因子完全随机设计,将40对种黑豚随机分成对照组、试验Ⅰ组、Ⅱ组、Ⅲ组4个处理组,分别饲喂在基础日粮中添加0、0.5、1.0、2.0g/kg复合微生态制剂的日粮,试验结束测定平均产仔数、平均活仔数、平均活仔率、仔黑豚初生平均重、泌乳力、总耗料量、料乳比、仔黑豚平均日增重、仔黑豚平均成活率等指标。结果显示:试验Ⅰ组的料乳比较对照组降低3.40%(P<0.05);试验Ⅱ组的平均活仔数、平均活仔率、初生平均重、泌乳力、总耗料量、平均日增重、平均成活率较对照组分别提高19.44%、19.87%、2.82%、28.80%、21.21%、4.05%、18.01%(P<0.05),料乳比较对照组降低5.97%(P<0.05);试验Ⅲ组的平均活仔数、平均活仔率、初生平均重、泌乳力、总耗料量、平均日增重、平均成活率较对照组分别提高22.22%、19.23%、2.77%、26.91%、19.48%、3.81%、15.12%,料乳比较对照组降低5.88%(P<0.05);试验Ⅱ组与试验Ⅲ组之间,各检测指标差异均不显著(P>0.05)。综上,复合微生态制剂可显著提高母黑豚繁殖性能、泌乳性能和仔黑豚生长性能,其最适添加剂量为1.0g/kg。     

复合益生菌制剂对肉牛生长性能、屠宰性能及经济效益的影响

为研究不同水平的复合益生菌制剂对肉牛生长性能、屠宰性能及经济效益的影响,试验选择体重(200±4)kg肉牛60头随机分成4组,每组15个重复,每个重复1头,1组饲喂基础日粮为对照组,试验2、3、4组分别添加2.5%、5.0%、10%复合益生菌制剂,预试验7 d,试验期为56 d。结果表明:(1)试验3、4组的平均日增重较1组比分别提高19.4%、18.1%(P<0.05),试验3、4组料重比较1组比分别降低9.6%、7.2%(P<0.05),试验2、3、4组的平均采食量均高于1组(P>0.05);(2)试验2、3、4组的胴体重、屠宰率均高于1组(P>0.05),试验3、4组的宰前活重、眼肌面积较1组比分别提高10.3%、9.0%、14.3%、13.9%(P<0.05);(3)试验2、3、4组试验肉牛的每千克增重成本均低于1组,试验3、4组每千克增重的饲料成本分别减少1.0元和0.77元。综上,不同水平复合益生菌制剂的添加可以提高肉牛的生长性能、屠宰性能及经济效益,以5.0%添加为适宜。     

枯草芽孢杆菌对肉鸡生产性能、屠宰性能、免疫性能和肌肉风味的影响

为研究枯草芽孢杆菌对肉鸡生产性能、屠宰性能、免疫性能和肌肉风味的影响,本试验在基础日粮中添加0.1%枯草芽孢杆菌制剂,添加量分别为5×10^8、8×10^8cfu/kg,进行为期42d的饲养试验,试验结束后称重、屠宰和剖解。结果表明:添加枯草芽孢杆菌对AA肉鸡的日增重、料重比、屠宰率、全净膛率、半净膛率、腹脂率、免疫器官指数、以及胸腿肉中的脂肪、肌苷酸、单不饱和脂肪酸都有极显著(P<0.01)的促进作用,而剂量高低对料重比、腹脂率、免疫器官指数、脂肪、肌苷酸、单不饱和脂肪酸和多不饱和脂肪酸(胸肉)均能产生极显著(P<0.01)的影响,成活率和肌苷酸比对照组差异显著(P<0.05),其他指标无显著影响。     

Effect of feather meal on barrow performance

One hundred ninety-six crossbred barrows of high lean gain potential (21.2 kg BW) were used in an experiment to determine the effect of dietary feather meal (FM) on barrow performance, specifically, the effects of the ingredient on ADG and carcass leanness. Additionally, 28 gilts (26.8 kg BW) were used to compare gender differences on the corn-soybean meal control diets. Treatments were control barrows and control gilts fed corn-soybean meal diets, and barrows fed according to a 2 x 3 factorial arrangement of FM levels (10 or 20%, as-fed basis) and starting weights on the diets (36, 60, or 86 kg BW). All barrow diets were formulated to contain the same apparent digestible lysine and ME. Control barrows ate more feed (2.61 vs. 2.39 kg/d; as-fed), grew faster (0.911 vs. 0.827 kg/d), had greater backfat depth at slaughter (15.6 vs. 11.6 mm), and had lower carcass lean content (P < 0.001), with no difference in daily lean gain (P = 0.848) compared with gilts. There was a linear (P = 0.010) decrease in ADG for barrows fed increasing amounts of FM from 36 kg BW to slaughter, with no effect of FM additions on ADG when initiated at 60 or 86 kg BW. There was a quadratic reduction (P = 0.008) in ADFI and estimated digestible lysine intake with increasing FM for the 36 to 60 kg BW period for barrows fed FM starting at 36 kg BW. There was a linear (P = 0.006) decrease in ADFI for the 60 to 86 kg BW period with increasing FM for barrows started on FM at 60 kg BW. There was no effect of experimental diets or starting weight on barrow 10th-rib backfat depth at slaughter. These results suggest that diets containing 10 and 20% FM were effective in decreasing overall ADG and ADFI by barrows when feeding of FM was initiated at 36 kg BW; however, backfat at slaughter was still greater than for control gilts.     

Feedlot performance of hysterectomized and ovariectomized heifers

Seventy-five crossbred heifers (mean weight 304 kg) were stratified by weight and source and placed in eight pens. Four duplicate treatments were randomly assigned to pens as follows: (1) intact-control (n = 19), (2) intact + melengestrol acetate (MGA, n = 20), (3) hysterectomy (n = 17) and (4) ovariectomy (OVX, n = 19). All heifers were preconditioned for 2 mo before beginning the finishing study. Surgery was performed through a high lumbar incision approximately 3 wk before the finishing study began. Group 2 heifers were fed .4 mg X head-1 X d-1 MGA. Blood samples were collected at 28-d intervals throughout the 112-d finishing phase. Ovaries were collected at slaughter and carcass data were obtained 24 h after slaughter. On d 112, progesterone was higher (P less than .05) in hysterectomized heifers than in other treatment groups. Serum progesterone concentration was nondetectable (less than .35 ng/ml) in OVX and MGA heifers. There were no differences (P greater than .05) in feed efficiency or carcass characteristics among the four treatments. Hysterectomized and MGA heifers had similar (P greater than .05) average daily gains, which were higher (P less than .15) than control and OVX heifers. These data suggest that the elevated levels of progesterone from the maintained corpora lutea and the subsequent absence of estrous activity in the hysterectomized heifers are advantageous for promoting growth in feedlot heifers.     

Effect of wean-to-finish management on pig performance

In each of three trials, 240 crossbred barrows weaned at 17 d of age (5.1 kg BW) were assigned to one of three experimental treatments based on light and heavy weight outcome groups. Experimental treatments were 1) wean-to-finish at 0.69 m2/pig and 15 pigs/pen; 2) wean-to-finish double-stocked at 0.35 m2/pig, 30 pigs per pen for 8 wk and then randomly split into two pens (either stayed in same pen or moved to new pen) for growth to slaughter at 0.69 m2/pig; and 3) nursery facility for 8 wk at 0.35 m2/pig and 15 pigs/pen followed by move to the same grow-finish facility housing wean-to-finish and double-stocked pigs and maintaining pen integrity. Beginning at 38 kg BW, diets were supplemented with either bacitracin methylenedisalicylate at 33 mg/kg to slaughter or tylosin at 44 mg/kg to 59 kg BW and 22 mg/kg thereafter. There were no trial x treatment interactions, even though there was considerable variation in health status among trials. At the end of the 56-d nursery period, wean-to-finish pigs weighed more than nursery (28.7 vs 27.7 kg; P = 0.071) and double-stocked pigs (28.7 vs 26.9 kg; P = 0.002), due to greater ADG (wean-to-finish vs nursery; P = 0.062; wean-to-finish vs double-stocked; P = 0.002) and greater ADFI (wean-to-finish vs nursery; P = 0.024; wean-to-finish vs double-stocked, P = 0.002). There was no effect of treatments (P > 0.1) on ADG, feed conversion, carcass lean percentage, or lean gain during the growing-finishing period. There was also no effect of treatment (P > 0.1) on ADG or ADFI from weaning to slaughter. There was no difference (P > 0.1) between bacitracin methylenedisalicylate and tylosin for ADG, feed conversion, carcass lean percentage, or daily lean gain. These data suggest that housing 5-kg weaned pigs in fully slatted growing-finishing facilities from weaning to slaughter was not detrimental to overall performance. In this experiment, dietary additions of bacitracin methylenedisalicylate or tylosin from 38 kg BW to slaughter weight resulted in similar growth performance.     

饲料中添加刺五加提取物对肉鸡生长性能、屠宰性能及经济效益指标的影响

为探讨饲料中添加刺五加提取物对肉鸡生长性能、屠宰性能及经济效益指标的影响,试验选择体重相近的21日龄白羽肉鸡400只,随机分成4组,每组10个重复,每个重复10只,1组为空白对照组饲喂基础日粮,试验2、3、4组分别在基础日粮中添加1.0%、2.0%、3.0%的刺五加提取物,预试验7 d,试验期为21 d。结果表明:(1)试验2、3、4组的平均日采食量均高于1组(P>0.05),试验3、4组的平均日增重较1组比分别提高11.8%、10.3%(P<0.05),料重比较1组比分别降低16.7%、15.0%(P<0.05);(2)试验2、3、4组的屠宰率、全净膛率、半净膛率均高于1组(P>0.05),验3、4组的胸肌率、腿肌率较1组比分别提高15.3%、14.0%、21.9%、15.1%(P<0.05);(3)试验3、4组每只肉鸡经济效益较1组比分别提高11.6%、10.6%。综上,饲料中不同水平的刺五加提取物添加均可以提高白羽肉鸡的生长性能、屠宰性能及经济效益,以2.0%添加为适宜。     

青贮玉米秸秆对肉牛生长性能和屠宰性能的影响

为研究青贮玉米秸秆对肉牛生长性能和屠宰性能的影响,试验选取体重相近的11~12月龄西门塔尔杂交公牛30头,随机分为3组,每组10个重复,分别饲喂风干玉米秸秆(CS)、风干玉米秸秆与青贮玉米秸秆1:1(CSS)、青贮玉米秸秆(SS),每天饲喂等量的精料,试验期60d。结果表明:CSS、SS组较CS组平均日增重分别增加24.2%、44.0%(P<0.05),料肉比分别降低15.1%、24.7%(P<0.05);SS组较CSS组平均日增重增加15.9%,料肉比下降11.25%(P<0.05)。CSS、SS组较CS组热胴体重分别增加14.1%、26.1%(P<0.05),屠宰率分别增加9.9%、18.1%(P<0.05),净肉率分别增加6.0%、7.9%(P<0.05);SS组热胴体重、屠宰率较CSS组分别增加10.5%、7.4%(P<0.05),其余指标无显著差异(P>0.05)。综上,饲喂青贮玉米秸秆能显著改善肉牛生长性能及屠宰性能。     

低聚寡糖对仔猪生产性能的影响

通过在基础日粮中分别添加 2种不同寡聚糖和抗生素比较其对仔猪的生长性能、腹泻率及料重比的影响。选用 9窝 72头平均日龄为 41d的长白×皮特兰×枫泾三元杂交断奶仔猪进行试验。试验分 3组 ,每组 2个重复。对照组 (Ⅰ )为抗生素组 ,试验组Ⅱ为甘露寡糖组 ,试验组Ⅲ为低聚果糖组。 2 8d的饲养试验表明 :Ⅱ、Ⅲ组在试验 1～ 4周全程体增重分别为 (6 2 5± 1 81 )kg和 (6 0 3± 2 59)kg ,日增重分别为 (2 2 3 0 7±64 54)g和 (2 1 5 33± 1 0 0 91 )g,均显著高于Ⅰ组体增重 (5 36± 2 0 6)kg和日增重 (1 91 37± 73 55)g(P <0 0 5) ;Ⅰ组的腹泻率为 (4 90±4 48) % ,低于Ⅱ组 (5 64± 4 40 ) %和Ⅲ组 (6 37± 5 33) % ,Ⅲ组腹泻较严重 ,但各组间差异不显著 (P >0 0 5) ;1～ 4周试验全程Ⅱ组和Ⅲ组的料重比分别为 (2 0 0± 0 2 5)和 (2 0 9± 0 0 8) ,均显著低于Ⅰ组 (2 41± 0 1 3) (P <0 0 5)。结果表明 :Ⅱ、Ⅲ组低聚寡糖的使用效果明显优于Ⅰ组抗生素。寡聚糖在一定程度上可替代抗生素 ,且不同低聚寡糖的饲喂效果存在差异。     

青贮杂交构树对育肥肉羊生长性能、屠宰性能及器官指数的影响

试验旨在研究不同添加比例青贮杂交构树对育肥肉羊生长性能、屠宰性能及器官指数的影响,探讨青贮杂交构树替代豆粕作为蛋白质原料饲喂肉羊的可行性。试验选取体重(26.25±1.92)kg的杜泊×湖羊F1代公羊48只,随机分为4组,每组12只羊,对照组(CG组)、试验组(LG组、MG组、HG组)分别饲喂添加0%、6%、12%和18%青贮杂交构树而营养水平相同的试验饲粮,试验期90 d。结果表明:(1)CG、LG、MG、HG组间平均日采食量、料肉比、器官指数均无显著差异(P>0.05);(2)HG组屠宰率较CG组降低10.9%(P<0.05);(3)MG组增重最大,料肉比最低,增重盈利比CG组高54.37元。综上,育肥肉羊日粮中用适量青贮杂交构树替代豆粕作为蛋白质饲料是可行的,且可降低饲料成本,适宜的日粮配方可提高动物增重和饲养收益,对发展节粮型肉羊养殖业具有推广价值,本试验条件下,以添加12%青贮杂交构树经济效益最高。     

酵母培养物对蛋鸡生产性能及免疫性能的影响

为研究酵母培养物对蛋鸡生产性能及免疫性能的影响,本试验选用健康、体重相近的23周龄海兰褐蛋鸡120只,随机分成2个组,每组设3个重复,每个重复20只鸡。其中一组为对照组,饲喂基础日粮;另外一组为试验组,饲喂基础日粮中添加0.3%酵母培养物日粮,其他条件均保持一致,试验期共6周。试验结果表明:(1)在基础日粮中添加0.3%的酵母培养物可极显著提高4 ~ 6周的蛋重(P < 0.01),试验组比对照组提高了2.33%;但对蛋鸡的平均日采食量、产蛋率和料蛋比无显著影响(P > 0.05)。(2)添加0.3%酵母培养物可极显著提高第3周末血清中IgG含量(P < 0.01),提高了21.74%;并且可极显著提高第6周末血清中IgM和IgG的含量(P < 0.01),分别提高了10.69%和16.15%;对IgA有提高的趋势,但是差异不显著(P > 0.05)。由此试验表明添加0.3%酵母培养物可有效提高鸡蛋蛋重,并且可以极显著提高蛋鸡的免疫性能。     

合生素对肉仔鸡生长性能的影响

为探讨合生素在肉仔鸡生产中的最适添加量及其对肉仔鸡生产性能的影响,本文采用0.05%和0.10%两个比例添加合生素,其余3组为益生素组、抗生素组和对照组。对6000只AA公雏鸡进行为期7周的试验。结果表明:合生素组(0.05%和0.10%)的平均日采食量、日增重和饲料转化率都优于益生素组和抗生素组,但差异不显著(P>0.05);平均采食量(0￣3、4￣6、6￣7周龄)和平均日增重(0￣3、6￣7周龄)显著高于对照组(P<0.05);添加0.05%的合生素组与0.10%的合生素组对肉仔鸡生产性能有相同的效果(P>0.05)。说明由益生素与植物提取物组成的合生素可以替代抗生素和益生素在肉仔鸡生产中应用,其最适的添加量为0.05%。     

Photoperiod and heat stress influence on lactating sow performance and photoperiod effects on nursery pig performance

Three experiments were conducted to evaluate sow and piglet productivity under extended photoperiod. In Exp. 1, 98 crossbred, lactating sows were housed in one of four treatments: thermoneutral air temperature (23.6 degrees C) in either (h of light:dark) 1:23 or 16:8 photoperiods, or heat stress (30.4 degrees C) in either 1:23 or 16:8 photoperiods. Heat stress reduced (P less than .05) sow feed intake, piglet mortality and piglet weaning weight and increased (P less than .01) sow lactation weight loss. Number of pigs weaned per litter was increased (P less than .01) when sows were heat-stressed. Extended photoperiod reduced (P greater than .05) time for sows to rebreed postweaning by .4 d. The interaction between air temperature and photoperiod was significant only for sow lactation weight loss. Heat stress increased sow lactation weight loss, but this effect was more severe in the 1:23 than in the 16:8 photoperiod. Experiments 2 and 3 examined the effects of 1:23 or 16:8 photoperiods on nursery pig performance when pigs were weaned from sows experiencing 1:23 (Exp. 3) or 16:8 (Exp. 2) photoperiods. In both nursery studies, photoperiod did not influence (P greater than .10) postweaning pig mortality, feed intake, weight gain or gain:feed ratio. In conclusion, extended photoperiod reduced days to return to estrus and reduced sow lactation weight loss, especially during heat stress. No benefits in preweaning or postweaning piglet weight or survival were observed by use of extended photoperiod.     

Genetic analysis of racing performance in Irish greyhounds

The aim of this study was to analyse racing performance data in Irish greyhounds with regard to genetic and environmental variation. Estimation of heritabilities for racing time (RT) and ranking, and the prediction of breeding values for all greyhounds in the investigated data were carried out. Data from 42,785 races in Ireland in the years 2000-2003 were available. These results were obtained from 42,880 greyhounds on 20 race tracks over a distance of 480 m. Three traits were analysed, RT, ranking and a scaled logarithmic function for RT (ART), which was used to adjust racing time to be normally distributed. The data were analysed with a bivariate animal model. The estimated heritabilities were moderate for RT (0.31) and ART (0.38), but very low for ranking (0.10). The repeatabilities were 0.56 (RT), 0.51 (ART) and 0.13 (ranking). The genetic correlations were very high, 0.99 (RT-ranking) and 0.96 (ART-ranking), while the phenotypic correlation was lower, 0.60 (RT-ranking) and 0.62 (ART-ranking). The genetic trend for the traits as well as the phenotypic change of the average RT was positive.     

Variability of performance of wound infusion catheters

ObjectiveTo compare the distribution of flow from two commercial and one handmade multihole wound infusion catheters.Study designOpen label experimental measurement of flow distribution in a bench top apparatus of handmade (n = 10) and two commercial (n = 10 each) wound infusion catheters with 5–6″ (12–15.2 cm) long diffusion surfaces.MethodsThe distribution of 6 mL of distilled water injected at three different injection speeds (0.5, 5, and 120 minutes) through individual triangular pieces of felt cloth fitted over six contiguous regions of the diffusion surface of each catheter was measured in triplicate.ResultsThe distribution of flow through the six regions was significantly more uniform at the two faster injection speeds. Ninety two per cent of the 120 minute infusion trials resulted in one or more regions producing negligible flow (<5% of total output), and in 16% of the 120 minute trials all the flow came from just one or two regions.ConclusionsConstant-rate infusions of 3 mL hour^?1 provide erratic distribution of flow from wound infusion catheters in a bench top apparatus. Commercial catheters did not outperform handmade catheters.Clinical relevanceUneven distribution of flow at low infusion speeds may contribute to inconsistent or unsatisfactory pain relief in patients treated with continuous wound infusions of local anesthetics.     

Halothane gene and swine performance.

One hundred thirty-one pigs representing seven different breed groups (Minnesota No. 1 [M], Pietrain [P], Yorkshire [Y], and crosses PY, P[PY], P[NP], and P[YP]P) and three halothane gene genotypes (NN, Nn, and nn) were tested for breed, sex, and halothane gene (HAL) effects on growth and carcass performance. Breed effects were significant for all traits measured. Sex effect was significant for most traits except for meat scores. The HAL-locus linkage group explained 20 to 30% of the total variation for meat quality scores and 1 to 10% for meat quantity and growth traits. Pietrain x Yorkshire was the fastest growing breed group and had relatively good carcass quality. Pietrain and its related crosses had the most lean muscle but the lowest meat quality. The HN (HAL negative, genotype Nn) individuals within the PPY and PNP groups grew more quickly and had higher meat quality scores and less muscling than HP (HAL positive, genotype nn) individuals. A second experiment with 40 pigs showed significant differences in fat concentration in the loin muscle between breeds (M, Y, and P) and between genotypes within the NP population (NP[HP] and NP[HN]). The phenotypic correlation between fat percentage and marbling was .59 (P less than .01). The NP(HP) had higher water percentage in lean than the NP(HN). The water percentage was negatively correlated with meat quality scores of color, firmness, and marbling with phenotypic correlations of -.10, -.23, and -.57 (P less than .01), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Breed effects on crossbred cow-calf performance

Effects of seven breeds of cow's sire and 12 breeds of cow's maternal grandsire on preweaning performance of crossbred cows and their calves were examined in data from two experiments conducted at the Roman L. Hruska U.S. Mean Animal Research Center. Data included 1,836 records over three to five parities for 516 cows by 143 sires and by 307 maternal grandsires. The statistical model fitted effects of calf sex, parity, cow birth-breeding year or cow-calf birth year, the breed effects and their interactions. Deviations of breed of sire or equivalent grandsire effects on each trait from the mean for Hereford x Angus cows ranged from -1.6 to 5.5 kg (P less than .001) for calf birth weights, -15 to 1% (P less than .001) for calving difficulty, nonsignificant for preweaning calf mortality and -2 to 27 kg (P less than .001) for calf weaning weight. Deviations were nonsignificant for conception rate and calves weaned per cow exposed to breeding, but -2 to 40 kg (P less than .001) for calf weight weaned per cow exposed for breeding, -7 to 78 kg (P less than .001) for cow weight and -20 to 2% (P less than .001) for body condition score. The advantages of Holstein and Brahman cross over Hereford x Angus cows of 23 and 13% in weight of calf weaned/cow-breeding exposure must be compared with the expected greater feed requirements from 7 or 8% heavier cows and at least 50% higher milk production, which emphasizes the need to include input measures and costs in breed evaluation schemes.     

Total blood volume and thoroughbred racing performance

Total blood volume (TBV) was measured on 47 mature race-retired Thoroughbreds and compared with individual performance records. TBV had a near normal distribution with a mean of 49.2 ± 5.0 L. Thirty-three of the 47 horses (70.2%) were stakes horses (SH). There was a difference (P < .01) in the percentage of SH with below average (BA) TBV (36.4%) compared with the percentage of SH with average (A) TBV (73.1%) and an even greater difference (P < .001) when compared with horses with above average (AA) TBV (100%). Further, there was a difference (P < .001) in the percentage of graded stakes horses (GSH) with BA-TBV (0%) compared with those with A-TBV (23.1%) and AA-TBV (30%). TBV was related (P < .05) to overall performance level (r = 0.45). There was no difference in the average earnings per start (AEI) of horses with BA- and A-TBV; however, horses with AA-TBV had a higher (P < .05) AEI, and overall TBV was related to AEI (r = 0.34). TBV is a measure of oxygen delivery capacity, and since it is inherent to the individual, values from yearlings and unraced 2-year-olds should provide buyers with an objective, performance-related physiologic parameter to use in selection.