猪IGF-Ⅰ基因的一个遗传多态性及其遗传效应分析

采用PCR-SSCP方法对长白猪(87头)、大白猪(79头)和马身猪(102头)的胰岛素样生长因子-Ⅰ(IGF-Ⅰ)基因外显子3和外显子4分别进行单核苷酸多态性分析.发现外显子3上有多态性,且存在3种基因型(AA、AB、BB).统计结果表明,3种基因型在各品种中的分布不一致,多重比较差异极显著(P＜0.01).固定效应模型分析结果表明,背膘厚基因型间差异显著(P＜0.05),而初生重、断奶重和6月龄重基因型间差异不显著(P＞0.05).最小二乘分析结果表明,BB基因型与其它2种基因型比较有较大的初生重,同AA和AB型比较差异极显著(P＜0.01),3种基因型在初生重的大小排列顺序为AA＜AB＜BB;BB基因型与AA基因型比较有较小的背膘厚,且差异极显著(P＜0.01).因此,推测IGF-Ⅰ基因对个体的初生重和胴体瘦肉率存在一定的影响.选择带有B等位基因的个体,有望提高个体的初生重和胴体的瘦肉率.     

影响山西肉用绵羊母本品系生长性状的非遗传因素分析

为研究非遗传因素对山西肉用绵羊母本品系的初生重、断奶重(100日龄)、6月龄重和周岁重的影响,收集了山西肉用绵羊母本品系育种记录.利用SPSS 19.0的GLM过程分析性别、出生年份、出生月份、母亲年龄、出生类型对山西肉用绵羊母本品系生长性状的的影响.结果表明:性别仅对6月龄重有极显著影响(P＜0.01),对初生重、断奶重、周岁重影响显著(P＜0.05);出生年份对初生重和断奶重有极显著影响(P＜0.01),对6月龄重和周岁重影响显著(P＜0.05);出生月份对6月龄重有极显著影响(P＜0.01),对初生重、断奶重和周岁重无影响(P＞0.05);母亲年龄对初生重影响显著(P＜0.05),对6月龄重影响极显著(P＜0.01),而对断奶重和周岁重无影响(P＞0.05);出生类型对6月龄重有显著影响(P＜0.05),对初生重和断奶重有极显著影响(P＜0.01).本分析结果对山西肉用绵羊母本品系的进一步选育和生产具有重要参考价值.     

干旱区湿地芦苇各器官生态化学计量对土壤因子的响应

了解植物养分浓度及其化学计量对土壤因子的响应,对预测脆弱而敏感生态系统对环境变化的响应至关重要。以敦煌阳关湿地优势种芦苇(Phragmites australis)为对象,通过野外调查与实验分析,研究芦苇不同器官生态化学计量特征及其影响因素。结果表明:芦苇各器官C、P含量为叶>根>茎,N含量及N∶P为叶>茎>根,C∶N为根>茎>叶,C∶P则为茎>根>叶。叶、根C含量显著高于茎(P<0.05),叶、根C含量之间无显著差异(P>0.05),根、茎和叶N、P含量及C∶N、C∶P和N∶P差异显著(P<0.05);芦苇根N∶P<14,叶片N∶P>16,茎N∶P介于14~16;C含量在各器官之间均无显著相关性(P>0.05),根与茎、叶N含量之间呈极显著正相关(P<0.01),根与茎P含量呈极显著正相关(P<0.01),茎与叶N含量呈显著正相关(P<0.05);土壤盐分与芦苇根和茎N含量呈极显著正相关(P<0.01),土壤P含量与茎P含量呈极显著正相关(P<0.01),土壤有效P与根、茎N含量呈极显著正相关(P<0.01);土壤P是影响芦苇根、茎化学计量的主要因素,土壤盐分是影响叶片化学计量的主要因素,芦苇趋向提高各器官N含量来应对高盐、低P的土壤环境。     

胡杨异形叶结构型性状及其与胸径关系

对胡杨5种类型植株的叶片厚度、叶面积、比叶面积、叶片干重和干物质含量等5个结构型性状指标进行分析,研究叶片的结构型性状与胸径之间及各个结构型性状彼此间相互关系。结果表明:叶面积、叶厚度和叶干重与胸径呈极显著正相关(P0.01),叶片干物质含量与胸径间呈显著正相关(P0.05),比叶面积与胸径之间呈极显著负相关(P0.01),说明随着植株生长发育的进行,叶片的面积、厚度、干重和干物质含量均逐渐增加,而比叶面积逐渐减小。各性状指标间相关性表现为叶面积、叶厚度、叶干物质和叶片干物质含量任意2个指标之间均呈显著或极显著正相关;而比叶面积与这4个指标间均呈显著或极显著负相关。     

中药组方“回乳康”对回乳期奶牛血清PRL、GH和STAT5含量的影响

为探究中药组方"回乳康"对回乳期奶牛血清催乳素(PRL)、生长激素(GH)和信号转导和转录激活因子5(STAT5)含量的影响。试验选择规模化奶牛场产奶量为15.42±0.71 kg的妊娠后期,即将干乳的健康奶牛80头。随机分为A、B、C和D组,每组20头,采用逐渐干奶法回乳,干乳开始当天记为第0 d,A组为对照组,不饲喂"回乳康",B、C、D组均从回乳开始第1 d,每日上午8:00分别饲喂"回乳康"400、500、600 g,回乳完成后停止饲喂。分别采集奶牛回乳期第0、1、3、5、7、9和11 d尾静脉血,并记录奶牛单日产奶量,ELISA法检测血清PRL、GH和STAT5含量。结果显示,各组回乳期奶牛产奶量均随时间推移降低,A、B、C和D组回乳时间分别为11、7、5和5 d。各组PRL、GH和STAT5含量均呈下降趋势,GH和STAT5含量在回乳期后回升,且A组下降趋势较各中药组慢,C组PRL、GH、STAT5含量及产奶量均分别与D组差异不显著(P0.05);回乳期奶牛血清PRL、GH、STAT5含量与产奶量两两间均呈极显著正相关(P0.01)。综上,饲喂500 g/日"回乳康"即可使奶牛回乳效果达到最佳。     

青海省药用植物龙葵栽培前后光合特性的比较

为了揭示青藏高原地区药用植物龙葵栽培前后的光合生理特性,本文采用常规光合指标测定方法对青海省药用植物龙葵栽培前后光合特性进行比较研究.结果显示:(1)野生龙葵的Chla、Chlb和Chlt含量低于栽培龙葵的,其中两者Chla含量间存在显著差异(P＜0.05),Chlb和Chlt含量间差异极显著(P＜0.01);(2)野生龙葵的Car、Chla/Chlb、Chlt/Chlt则明显高于栽培的,其中Car、Chla/Chlb间存在显著差异(P＜0.05),Car/Chlt间差异不显著(P＞0.05);(3)野生和栽培龙葵的净光合速率日变化类型均为双峰曲线型,但总体趋势表现为野生龙葵的低于栽培龙葵的;(4)相关分析表明,光合有效辐射与Pn间呈极显著负相关关系,相对湿度与Pn间呈极显著正相关关系,细胞间隙CO2浓度、气温与Pn呈显著负相关关系,瞬时水分利用效率与Pn间呈显著正相关关系.研究表明,栽培前后抗性生理指标的变化是青藏高原低温、低气压、强辐射等多种逆境生态因子长期作用的结果,是植物对生态环境的一种生理性适应.     

糖耐量减低患者血清瘦素与内皮素-1 的测定及其临床意义

目的:探讨糖耐量减低(IGT)患者血清瘦素(Leptin)和血浆内皮素-1(ET-1)含量变化及其意义。方法:采用放射免疫法检测65例IGT患者、50名正常健康体检者和50例2型糖尿病患者血清中Leptin和ET-1的含量,同时分别测定体重指数、腰臀比、空腹血糖(FBG)、餐后2小时血糖(2h PBG)及空腹胰岛素(FINS),并用HOMA稳态模型计算胰岛素抵抗指数(HOMA-IR)。结果:糖尿病组、IGT组血清Leptin、ET-1、FBG、2hPBG、FINS、TC含量及HOMA-IR指数显著高于正常对照组(P<0.05),糖尿病组血清Leptin、ET-1、FBG、2hPBG、FINS、TC含量及HOMA-IR指数明显高于IGT组(P<0.05)。IGT组血清Leptin水平与BMI、血清ET-1、FBG、2hPBG、FINS、TC含量及HOMA-IR指数呈显著正相关(P<0.01),IGT组血清ET-1水平与收缩压、舒张压、BMI、血清FBG、2hPBG、FINS含量及HOMA-IR指数呈显著正相关(P<0.01)。结论:瘦素与内皮素-1均可能在IGT发展成2型糖尿病过程中起一定的作用。     

妊娠高血压患者血清瘦素、Cys C及beta-HCG水平检测的临床意义

目的:研究妊娠高血压患者血清瘦素、胱抑素C(Cys C)以及人绒毛膜促性腺激素(β-HCG)水平检测的临床意义。方法:选取2014年4月到2015年4月我院收治的妊娠高血压患者90例(妊娠高血压组),另选同期正常妊娠者90例(正常妊娠组),健康体检非妊娠妇女90例(对照组),测量三组血清瘦素、Cys C以及β-HCG水平,并分析各指标的相关性。结果:妊娠高血压组和正常妊娠组血清瘦素、Cys C以及β-HCG水平均显著高于对照组,比较差异具有统计学意义(P0.05),妊娠高血压组血清瘦素、Cys C以及β-HCG水平均显著高于正常妊娠组,比较差异具有统计学意义(P0.05);妊娠高血压越严重血清瘦素、Cys C以及β-HCG水平越高;妊娠高血压患者血清瘦素与Cys C和β-HCG均呈正相关关系(P0.05),Cys C与β-HCG也呈正相关关系(P0.05)。结论:检测血清中瘦素、Cys C和β-HCG水平有利于妊娠高血压的诊断,体检时发现上述物质异常升高要高度重视。     

壳斗科五树种幼苗叶片结构型性状及其相关关系

通过种子的人工采集、低温沙藏和温室培育后,将幼苗移栽到环境条件相同的同质园中自然生长,研究了中亚热带壳斗科丝栗栲(Castanopsis fargesii)、苦槠(C.sclerophylla)、锥栗(Castanea henryi)、板栗(C.mollissima)和麻栎(Quercus acutissima)2年生幼苗生长季节的叶面积、叶厚度、比叶面积、叶干物质含量、叶氮浓度、叶磷浓度和叶氮磷比7种结构型性状的差异及其相关关系。结果表明:(1)在5树种幼苗中,锥栗幼苗的叶面积和比叶面积最大、叶氮浓度最高,其叶干物质含量最低;丝栗栲幼苗的叶面积最小、叶氮浓度和叶磷浓度最低;苦槠幼苗的叶厚度和比叶面积最小,其叶干物质含量最高;板栗幼苗则是叶厚度最小;同时5树种幼苗叶片的氮磷比均无显著差异(P0.1)。(2)Pearson相关和线性回归分析表明,壳斗科5树种幼苗的叶面积与叶氮浓度极显著正相关(P0.01),并与比叶面积显著正相关(P0.05);叶厚度与比叶面积极显著负相关(P0.01),其与叶干物质含量显著正相关(P0.05);比叶面积与叶干物质含量极显著负相关(P0.01),并与叶氮浓度极显著正相关(P0.01),同时与叶磷浓度显著负相关(P0.05);叶氮浓度与叶干物质含量、叶磷浓度分别为显著负相关(P0.05)和显著正相关(P0.05)。该研究结果表明壳斗科5树种幼苗叶片的7种结构型性状表现出了一定的种间差异性,但同一结构型性状的大小顺序和种间差异的显著性不同;同时所有树种幼苗叶片各结构型性状间的相关性及其显著程度不同。     

多囊卵巢综合征患者胰岛素抵抗和胰岛β细胞分泌功能与氧化应激的相关性研究

目的:探讨多囊卵巢综合征(PCOS)患者胰岛素抵抗(IR)和胰岛β细胞分泌功能与氧化应激的相关性。方法:选择122名在大连市妇幼保健院生殖保健中心就诊的PCOS患者82例,包括IR组42例和非IR组40例,同期选取单纯因男性因素不育而月经规律、内分泌激素正常的对照组患者40例。检测空腹血糖(FBG)、空腹胰岛素(FINS)水平,测定血清活性氧(ROS)和丙二醛(MDA)含量以评价机体氧化应激,测定血清总抗氧化能力(TAC)和超氧化物歧化酶(SOD)含量评价机体的抗氧化能力,使用稳态模型评价机体的胰岛素抵抗(HOMA-IR)和胰岛β细胞分泌功能(HOMA-β)。结果:PCOS胰岛素抵抗组患者身体质量指数(BMI)、促黄体素(LH)、黄体生成激素/卵泡生成激素(LH/FSH)、睾酮(T)、FBG、FINS和HOMA-IR显著高于非IR和对照组,而HOMA-β显著低于非IR和对照组,差异均有统计学意义(P0.05);PCOS胰岛素抵抗组血清ROS和MDA含量较非IR组和对照组显著升高(P0.05),非IR组ROS含量显著高于对照组(P0.05),而非IR组和对照组MDA含量相比差异无显著性(P0.05);PCOS胰岛素抵抗组血清TAC和SOD含量较非IR组和对照组显著降低(P0.05),而非IR组血清TAC和SOD含量低于对照组,但差异无显著性(P0.05)。PCOS患者HOMA-IR与体质指数(BMI)及血清ROS和MDA水平呈正相关P0.01),与血清TAC和SOD活性呈显著负相关(P0.05)。结论:氧化应激与PCOS患者胰岛素抵抗密切相关,可能在其胰岛素抵抗发生发展进程中发挥着重要的作用。     

Variability of uterine blood flow in lactating cows during the second half of gestation

The main goal of the present study was to measure uterine blood flow volume (BFV) in the second half of gestation in lactating German Holstein cows. Furthermore, it was investigated, if there are individual variations in uterine blood flow and correlations between uterine blood flow and maternal weight and the birth weight of the calf. Forty-four cows were examined via color Doppler sonography in gestation weeks (GW) 21, 25, 29, 33, 37 and 39. The cows were allocated in groups based on the following variables: body weight (light ≤ 575 kg, heavy > 575 kg) and birth weight of the calf (light ≤ 42 kg, heavy > 42 kg). The BFV was measured via transrectal Doppler sonography of both uterine arteries. There was a linear increase in uterine BFV throughout the study period from 3053 ± 1143 ml/min to 16912 ± 5793 ml/min. Variation coefficients for inter-individual variations ranged from 34 to 37%. There was a moderate correlation between uterine BFV and birth weight of the calf in weeks 21 to 37 (0.30 ≤ r < 0.49; P < 0.05) and a good correlation in week 39 (r = 0.60; P < 0.0001). Uterine BFV in week 21 was significantly (P < 0.01) higher in heavy cows (3394 ± 1119 ml/min) than in light cows (2658 ± 1064 ml/min). Compared with light cows, the increase in uterine BFV was 32% higher in heavy cows during the study period. In week 21, there was no difference (P > 0.05) in uterine BFV between cows carrying a heavy calf (3351 ± 1130 ml/min) and those carrying a light calf (2796 ± 1115 ml/min). Thereafter, the increase of BFV was 43% higher in cows with a heavy calf than in those carrying a light calf. Cows with different body weights, but same birth weight of calf showed no differences (P > 0.05) in the increase of BFV, while in cows with the same body weight the rise in BFV was higher (P < 0.05) in those cows producing a heavy calf compared to cows carrying calves with light birth weights. In conclusion, there was a linear increase in uterine BFV in lactating Holstein cows during the second half of pregnancy with marked individual variations. Differences in the rise of BFV were more caused by the fetus than by body weight of cows.     

Abnormal offspring following in vitro production of bovine preimplantation embryos: a field study

Data on 944 calves from 2228 in vitro-produced (IVP) bovine preimplantation embryos were compared with data on 2787 AI calves born in the same herds in 1995. Bovine preimplantation embryos were produced in vitro following ovum pick up (OPU) from donor cows and pregnant heifers in an open nucleus breeding program. After 7 d of in vitro culture on a BRL cell monolayer in the presence of 10% FCS, frozen-thawed expanded blastocysts and fresh morulae to expanded blastocysts were transferred into recipient heifers and cows at 119 contracted farms throughout the Netherlands. The pregnancy rate, as confirmed by palpation per rectum between 90 and 150 d after transfer was 43.5% for both fresh and frozen embryos. Data on IVP and AI calves were registered by the farmers. The percentage of calves with a congenital malformation and the percentage of male calves were related to the total number of calves born. Gestation length, birth weight (measured by a balance), perinatal mortality and ease of calving were analyzed in a subdataset (699 IVP and 2543 AI calves, respectively) by a comparative analysis of variance (ANOVA). The ANOVA model included herd, month of calving, sire nested within AI or IVP, parity and breed of the inseminated cow/embryo recipient, sex of calf, type of calf (AI or IVP) and two-way interactions between type of calf and sex, parity and breed. The percentage of calves with congenital malformations was 3.2% and 0.7% for IVP and AI calves, respectively. An increased incidence of hydro-allantois and abnormal spinal cords and limbs was observed in IVP calves. The percentage of male calves was significantly different between IVP and AI, 55.5% and 48.9%, respectively (Chi-square, 1 degree of freedom, P < 0.05). On the average, IVP calves showed a significant increase of birth weight by 10% (4-5 kg), a 3-d longer gestation period, 2.4% more perinatal mortality and a more difficult calving process compared to AI calves (P < 0.05). From these results it is concluded that calves produced by IVP deviate significantly from calves produced by AI.     

Comparative cryopreservation of avian spermatozoa: effects of freezing and thawing rates on turkey and sandhill crane sperm cryosurvival

In beef cows, reduced energy intake delays first ovulation postpartum and is associated with lesser insulin, IGF-I and leptin concentrations. However, the close relationship among these hormones mask their individual roles in the reinitiation of ovarian activity. A β-adrenergic receptor agonist (βAR) was used to increase body condition score (BCS) and yet reduce body fat and leptin serum concentration to determine the specific role of leptin in the postpartum ovarian activity. Beef cows (n=77) with BCS 3.1 ± 1.4 received 2 kg/day of feed containing 0 or 0.15 mg/kg of zilpaterol (a synthethic βAR), for 33 days. Estrus was induced with a progestin implant applied for 9 d and cows in estrus were bred by artificial insemination (AI). Zilpaterol administration increased (P<0.05) daily weight gain, muscle depth and BCS, with no changes in back fat depth, reducing fat to muscle ratio (P<0.05). At the time of AI, insulin (38%) and IGF-I (26%) concentrations were less in zilpaterol-treated cows (P<0.05), but leptin concentration was unaffected. Ovulation rate and animal with luteal activity after estrus induction were also reduced by 35% (P=0.05) and 56.5% (P=0.007), respectively, in zilpaterol-treated cows. Logistic regression estimates for BCS (P=0.016) and IGF-I concentration (P=0.03) were positively related with the occurrence of luteal activity. In addition, whilst back fat (P=0.009) had a positive effect on luteal activity, leptin concentration did not show a significant relationship. In conclusion, despite an increase in body weight and a positive change in BCS, the reduction in insulin and IGF-I concentrations, associated with βAR treatment, reduced the response to induction of estrus. However only IGF-I, but not leptin or insulin, significantly influenced the odds for the occurrence of luteal activity after estrous induction in cattle with poor BCS.     

Short communication: Manipulation of neonatal leptin profile via exogenous glucocorticoids in beef calves

The link between circulating glucocorticoids and leptin in beef calves has not been explored but has been noted in several studies. The aim of this study is to determine the effects of exogenous glucocorticoids given at birth and 1 day of age on serum leptin concentrations in beef calves. Ruminant animals secrete leptin, which is thought to be important for the programming of the hypothalamic appetite centers. Angus crossbred cows (n = 31) bred via natural service were utilized for this experiment. At parturition (day 0), calf BW was recorded and each calf was infused intravenously with either a hydrocortisol sodium succinate solution (HC, 8 males and 8 females) at a dosage of 3.5 μg/kg of BW or a similar volume of saline solution (CONT, 7 males and 8 females). Each calf was given a second infusion of its respective treatment 24 h postpartum at 1.5 μg/kg of BW for HC treatment. Calf treatment was blocked by sex, dam body condition score (BCS), and dam age. Blood samples were taken via jugular venipuncture before infusion, daily from days 0 to 5, then every other day up to day 17. Serum leptin and cortisol concentrations were analyzed via radioimmunoassay. Dam age, dam BCS, calf BW, and serum leptin and cortisol concentrations were analyzed using MIXED procedure of SAS. Dam age was not different (P = 0.81) among HC and CONT calves (4.9±0.5 and 4.7±0.5, respectively). Dam BCS was not different between treatments (5.7±0.2 and 5.6±0.2 HC and CONT, respectively; P = 0.66). There was no difference in calf birth BW between treatments (P = 0.87) and averaged 38.3±1.4 kg. Cortisol concentrations were not different between both treatments (P = 0.23) from birth to day 4 of age. Calves that received the HC treatment showed significantly reduced (P = 0.03) leptin concentrations on days 1 to 13. Calf BW from 60 to 150 days of age was not different between CONT and HC treated calves (P = 0.65). These data indicate that exogenous glucocorticoids can be used to suppress neonatal leptin levels in calves. This could lead to changes in voluntary feed intake of treated calves.     

Influence of the dam and sire on size at birth and subsequent growth, milk production and fertility in dairy heifers

Genetic selection has resulted in larger cows with high milk production potential but a tendency for poor fertility. In multiparous cows fetal development competes for nutrients with concurrent milk production. This study tested the hypotheses that (a) maternal age and milk yield during pregnancy alter calf birth size and (b) birth weight influences subsequent productivity and fertility. Concurrently born Holstein-Friesian heifers (n=65) with multiparous dams and three sires were monitored from birth to the end of their first lactation to assess effects of birth weight on growth, milk production and fertility. Calves were analyzed as three subgroups: low (L), average (A) and high (H) birth weight (BW) calves (n=21-22 per group). LBW calves were born 10 kg lighter than HBW calves and remained significantly lighter throughout the study. They were generally smaller in other measured indices (length, height, girth, ponderal index) between birth and 9 months and were more likely to have older dams (lactations 3-6) with higher peak yields (>42 kg/day). Milk production parameters were indistinguishable between the 3 birthweight groups and metabolic parameters (IGF-I, insulin, glucose) measured around first calving were unaffected. HBW offspring were more likely to have persistent corpora lutea following their first calving and other fertility parameters also tended to be worse. Sire influenced gestation length but not birth size. Sire heritability estimates showed that weight, IGF-I and insulin concentrations after first calving and fertility in the first lactation were all heritable. The results support the hypothesis that high milk production in the dam may predispose to birth of a smaller calf. Smaller birth size did not, however, have any subsequent adverse effects on productivity or fertility in the first lactation and sire was more influential at this stage.     

Birth of large calves that developed from in vitro-derived bovine embryos

High birth weights were observed in calves that developed from bovine embryos produced by in vitro maturation (IVM) and in vitro fertilization (IVF) procedures. After IVM and IVF, embryos were either co-cultured in vitro with oviductal epithelial cells or transferred into the sheep oviduct for development to the blastocyst stage. Blastocysts were transferred to the reproductive tracts of recipient heifers and cows for development to term. Birth weights and gestation periods were compared between calves that developed from in vitro-derived embryos and calves born after artificial insemination (AI) of cows in the herd from which recipient females were selected. Gestation periods were not different among the groups (P > 0.05), but calves that developed from IVM/IVF-derived embryos co-cultured in vitro were larger at birth than calves born from IVM/IVF-derived embryos that developed into blastocysts in the sheep oviduct and calves born from AI (P < 0.001). Dystocia and calf mortality were associated with large calf size at birth. These data were collected from an experiment designed for other purposes, and confounding variables and small sample size could have influenced the observed differences in birth weights. Nevertheless, the extreme birth weights of some calves suggest that abnormal prenatal growth occurs in some IVM/IVF-derived bovine embryos and that conditions for co-culture to the blastocyst stage may exacerbate the problem.     

Effects of early separation on the dairy cow and calf: 2. Separation at 1 day and 2 weeks after birth

This study investigated the effects of separating dairy calves from their mothers at 1 day (early separation) and 14 days (late separation) after birth. Behavioural observations were conducted on 24 Holstein dairy cow–calf pairs during the first 24 h after separation. Before separation, cow–calf pairs were generally inactive. After separation, cows from the late-separation treatment group showed higher rates of calling, movement and placing the head outside the pen, than cows in the early-separation group. Parity did not influence cow behaviour. During the first 2 weeks after calving, cows in the late-separation group (i.e. still with their calves) yielded less milk at milking, a difference at least partly due to the milk consumed by the calf. Milk yields from days 15–150 did not differ between the two groups. After separation, calves in the late-separation group moved and placed their heads outside the pen more often than early-separation calves. During the first 14 days after birth, late-separation calves gained weight at more than three times the rate of those separated early. When introduced to an unfamiliar calf at 6 weeks of age, calves from the late-separation group showed more intense social behaviour towards the unfamiliar calf than did those calves separated early. Thus, the response to separation by both cows and calves increased when calves were separated at 2 weeks rather than 1 day of age, but calves separated at the later age gained more weight and delayed separation appeared to influence the development of calf social behaviour.     

Restricted dietary protein in pregnant beef cows: II. Effect on the immune response

Cows fed 0.37 Kg crude protein per day for four months before calving showed no decrease in colostral IgG, IgA, or IgM from cows fed a normal ration. Similarly, no difference in serum immunoglobulin concentration was detected in their calves. Cows in the low protein group developed significantly lower (P < 0.01) titers to Salmonella pullorum antigen than did the normal group. The data show significant positive linear regressions of calf agglutination titer to S. pullorum on the dam's colostral titers. Serum levels of IgG measured at 24 hours were significantly lower in calves from second-calf heifers than from these of other age groups. The IgA levels of serums from calves from the six-year-old cows were significantly higher than the serum levels of calves from younger dams (P < 0.01).     

Metabolic hormones,grazing behaviour,offspring physical distance and productive response of beef cow grazing at two herbage allowances

Herbage allowance (HA) management during gestation–lactation cycle of cows grazing native grasslands improves pregnancy rates and calves’ weaning weight records. Those improvements were associated with greater herbage mass, and better body condition score (BCS) and metabolic status of the cows, which could affect grazing and maternal behaviour, particularly when temporary suckling restriction (TSR) and flushing (FL) is applied. The objective of this study was to evaluate the effect of HA during the gestation–lactation period on cows’ and calves’ liveweight (LW), BCS, milk yield, insulin, IGF-1 and leptin concentrations, as well as the proportion of diurnal grazing activities (grazing, ruminating, walking and idling), and maternal behaviour from −10 to 70 days relative to TSR (day 0 = initiation of TSR at 86 ± 10 days relative to calving). Thirty-three primiparous Hereford cows were allocated to HA treatments during gestation and lactation, which annually averaged 2.5 (low = LHA) and 4 kg DM/kg LW (high = HHA). The LW and BCS of cows did not differ during −10 to 50 days but were greater in HHA than LHA at the end of the study (P < 0.05). Concentrations of IGF-1 were greater in HHA compared to LHA, while insulin and leptin did not differ. Grazing was lower in HHA than LHA, and the opposite occurred with ruminating and idling (P < 0.05). Cow–calf physical distance was greater in LHA cows compared to HHA (P < 0.05) and increased greatly in the former group after FL, while this increase was lower and later in HHA cows. Milk yield was greater in HHA (P < 0.05), and calves’ weight did not differ between treatments from day −10 to 35, but was greater in HHA compared to LHA from 45 days until the end of the study. Thus, the HHA in a low herbage height and mass condition resulted in greater IGF-1 concentrations and milk yield, and induced changes in grazing and maternal behaviour that were associated with increased cows’ LW, BCS and calves’ weight at the end of the study.     

Effects of early separation on the dairy cow and calf. 1. Separation at 6 h, 1 day and 4 days after birth

The aim of this study was to evaluate the effects of age of separation on the behavioural responses of the dairy calf and cow. Calves were separated from their dams 6 h, 1 day, or 4 days after birth (n=9 cow-calf pairs in each of the 3 treatment groups) and behaviour was video and audio taped from 1 h before separation to 21 h after separation. In the hour immediately before separation, we found that the younger calves tended to call and move more in the pen, and spent more time standing than the older calves, but after separation these trends reversed. Calves separated at older ages made significantly more movements in the pen (P<0.05), spent more time standing (P<0.05) and spent more time with the head out of the pen (P<0.01) than calves separated soon after birth. We observed a similar pattern for the cows. Before separation, cows with younger calves moved more frequently about the pen (P<0.05), and called at much higher rates (a mean of 40.7 calls during 40 min for cows on the 6-h treatment, vs. 0.2 calls for cows in the 4-day group; P<0.001). After separation, cows in the 4-day group called at approximately four times the rate of those separated at 6 h or 1 day (P<0.01). Moreover, the calls produced by cows separated later had a significantly higher fundamental frequency (P<0.001) and a lower emphasized harmonic (P<0.02) than the calls of cows separated from calves soon after birth. There was no difference between treatment groups in the other behavioural measures, either before or after separation. Calves separated at older ages tended to require fewer days of treatment for scouring, but calf weight gain and cow milk production did not differ among treatment groups. In conclusion, behavioural responses of both the cow and calf increase in relation to calf age at separation. However, there may be health advantages associated with delayed separation that compensate for the increased behavioural response.