影响哺乳期羔羊生长的母羊因素分析

为探索母羊因素对哺乳期云上黑山羊羔羊生长发育的影响,根据母羊体重、胎次分别选取云上黑山羊初生羔羊90只和120只,公、母各半,从出生开始直至90日龄断奶,每10天进行1次体重测定,进行生长发育分析。结果表明:(1)母羊产后体重对羔羊初生重、哺乳期体重具有显著影响(P<0.05)。母羔中,38~45 kg母羊组和48~62 kg母羊组的羔羊初生重、平均日增重均显著高于28~35 kg母羊组(P<0.05)。公羔中,38~45 kg母羊组的羔羊初生重显著高于其他两组羔羊(P<0.05),48~62 kg母羊组其羔羊平均日增重显著高于其他两组羔羊(P<0.05)。(2)母羊胎次对母羔初生重没有显著影响,但对母羔哺乳期体重均有显著影响(P<0.05),母羔中,3胎、4胎母羊组的羔羊平均日增重均显著高于1胎和2胎母羊组;母羊胎次对公羔的影响不显著。说明母羊产后体重显著影响羔羊胎儿期和哺乳期的生长发育,合适的母羊体重可以为羔羊提供充足的营养;母羊胎次仅对哺乳期母羔具有显著影响,母羊的母性行为随胎次的增加而完善。     

播期对河套地区玉米灌浆进度的影响

旨在为玉米的高产栽培提供理论支撑。采用分期播种法,利用试验数据,建立28个生长模型（方程均通过0.01的极显著检验）,将玉米灌浆期百粒干重、百粒体积随灌浆日数增加的时段分为三阶段,即渐增期、快增期和缓增期。适时播种的玉米吐丝后百粒体积、百粒干重增加进入渐增期,终止日分别为吐丝后的6天和20天,此后进入快速增长期,时间分别为22天和18天;其后到籽粒体积和干重增加进入缓慢增长期。适时播种的玉米百粒干重增加逐渐增长期为吐丝后活动积温区间0~502.4℃·d,增幅0.014 g/℃·d;快速增长期为吐丝后活动积温区间502.4~938.4℃·d,增幅0.049 g/℃·d;缓慢增长期为吐丝后活动积温区间938.4~1355.1℃·d,增幅0.018 g/℃·d。     

混合盐胁迫对马蔺幼苗根系构型及生长量的影响

为探讨不同种类盐胁迫对马蔺幼苗生长状况的影响,采用室内培养的方法,研究总质量浓度为0.3%的NaCl、NaHCO₃单盐溶液及其不同配比的混合盐溶液胁迫对马蔺(Iris lactea var. chinensis)幼苗生长量、地上部干鲜重比值、地下部干鲜重比值以及根系构型的影响。结果表明,随着胁迫时间的延长,0.3%NaCl溶液对叶数和株高增长量的影响最小,其次为3种混合盐溶液,各处理在第14天时株高增幅达到最大。经0.3%NaHCO₃处理后的幼苗地上部干鲜重的比值为空白对照的2.17倍,地下部干鲜重则为空白对照的56.61%,随着混合溶液中NaHCO₃浓度的上升,地上部干鲜重比值表现出上升的趋势,地下部干鲜重比值则表现出下降的趋势。经35天处理后,0.3%NaHCO₃胁迫的马蔺幼苗根系总长、根系表面积较对照均显著下降,降幅分别为39.73%、26.08%,而各处理间的根系体积却无显著差异。研究结果显示,0.3%NaHCO₃溶液对马蔺幼苗的胁迫作用最强,2种单盐对根系的胁迫作用强于混合盐胁迫,而0.3%NaCl溶液对生长量的胁迫作用最弱。     

苦瓜种子大小和单粒质量的遗传分析

以苦瓜自交系K7-359(P_1)和K7-422(P_2)分别作为母本和父本,通过杂交获得F_1,F_1自交获得F_2群体,采用主基因+多基因混合遗传模型分析苦瓜种子长度、宽度和单粒质量的遗传规律。结果表明,苦瓜种子长度和单粒质量的遗传均符合加性-显性-上位性多基因遗传模型(C-0模型),多基因遗传率分别为84.91%和76.55%,说明对苦瓜种子长度和单粒质量的选择宜在高世代进行;苦瓜种子宽度的遗传符合1对加性-显性主基因+加性-显性-上位性多基因模型(D-0模型),主基因和多基因遗传率分别为79.30%和3.86%,主基因遗传效应主要以加性效应为主,说明对种子宽度的改良可以采用组合育种的策略,且适宜在早期世代进行选择。     

同期排卵处理母牛体温和活动量变化规律及效果分析

为探究同期排卵处理母牛体温和活动量变化规律及不同同期排卵技术处理效果，指导同期排卵技术优化。本研究自动监测了18头20月龄左右同期排卵（GnRH-PG-GnRH）处理荷斯坦母牛和17头产后40~60 d预同期排卵（PG-PG-GnRH-PG-GnRH）处理荷斯坦母牛的体温和活动量，应用自动检测系统进行母牛发情监测。结果发现，同期排卵处理母牛发情时阴道温度平均升高（0.43±0.20）℃，持续（12.37±2.73）h；活动量平均升高（18.28±18.61）倍，持续（11.00±1.68）h；排卵时阴道温度平均下降（0.20±0.10）℃，持续（11.00±1.68）h。自动化发情监测显示，同期排卵处理母牛7头发情并排卵；预同期排卵母牛GnRH处理前全部发情排卵。两种同期排卵处理，虽可改变母牛性周期进程，促进母牛性周期同步化，但均难以使母牛性周期完全同步。因此，将同期排卵-定时输精和发情鉴定技术科学结合才能取得更好的繁殖效果。     

减氮配施有机肥对滴灌春小麦花后同化物转运和籽粒灌浆特性的影响

【目的】研究减氮条件下新疆滴灌小麦高产高效的调控途径,分析滴灌春小麦花后同化物转运和籽粒灌浆特性的调控效应,为新疆滴灌春小麦的高产优质栽培提供科学依据。【方法】设置不同减氮配施有机肥处理,采用裂区设计,氮素为主区,品种为副区;于2019年在田间滴灌条件下设置7种减氮配施有机肥水平(N_CK、N₅、N₁₀、N₁₅、N₂₀、N₂₅、N₀),比较分析不同减氮配施有机肥处理条件下,强筋小麦新春38号和中筋小麦新春49号的花后同化物转运及籽粒灌浆特性的变化。【结果】在灌浆期内,花后干物质(茎、叶)随灌浆期推进呈先升后降趋势,峰值出现在花后14 d,而穗干物质则呈逐渐增大的变化。随减氮配施有机肥程度增加,2个品种的花后干物质积累、花后干物质转移率、花后贡献率、粒重及灌浆各参数均呈现先增后减的趋势,在N₁₅处理下各指标均达到最优值,N₁₅>N₂₀>N₂₅>N₁₀>N₅>N_CK>N₀。2个品种的快速累积持续时间(t₂~t₁)、平均灌浆速率(V_mean)、最大灌浆速率(V_max)与粒重间均存在显著关系,且平均灌浆速率与粒重间的直接效应最大,2个品种的直接通径系数为1.034 7和0.957 3。在N₁₅处理下, V_mean相比其它处理分别增长了1.92%～30.58%(新春38号),1.02%～27.93%(新春49号)。【结论】在减氮配施有机肥处理下,以N₁₅处理(85%N+15%有机肥)的花后干物质积累量、花后转运率及贡献率最高,籽粒粒重最高,与之相关的灌浆各参数表现最优,即N₁₅处理为最优配比组合。     

Effects of dietary protein to energy ratios on growth,body composition and digestive enzyme activities in Chinese mitten‐handed crab,Eriocheir sinensis

This study aimed to determine the optimal protein to energy ratio (P/E ratio) and evaluate the effect of dietary protein and lipid levels on growth performance, body composition and digestive enzymes activities in Chinese mitten‐handed crab, Eriocheir sinensis. Nine practical diets containing three levels both for protein (DP 30%, 35% and 40%) and lipid (DL 2%, 7% and 12%) with P/E ratios ranging from 13.69 to 19.79 mg KJ^?1 were fed to four replicates of crabs (3.39 ± 0.10 g) for 10 weeks. Weight gain increased significantly with the increase in DP level at each DL level. Moreover, weight gain increased in crabs fed with diets containing DL level from 2% to 12% and DP level from 30% to 35%. However, the diet containing 40% DP and 12% DL levels significantly decreased the growth performance and protein efficiency of the crabs. The whole crab and hepatopancreas lipid contents also increased as dietary lipid increased, but not dietary protein. The total protease activity increased significantly with the increase in dietary protein at each lipid level. The lipase activity was statistically comparable among different DL levels at each DP level. Taken together, the crab fed the diet containing 35% protein and 12% lipid levels with P/E 15.77 mg KJ^?1 revealed optimal growth, feed utilization efficiency and digestive enzymes activities. Moreover, our study indicated that the higher dietary lipid level at a relatively lower dietary protein level could provide protein sparing effect in Eriocheir sinensis.     

Effect of dietary phosphorus levels on growth and body composition of crucian carp,Carassius auratus under indoor and outdoor experiments

Indoor and outdoor experiments were carried out simultaneously to evaluate the effects of dietary phosphorus levels on growth performance and body composition of crucian carp. Monocalcium was used to formulate extruded feed containing available phosphorus (AP) of 1.5 (D1), 4.7 (D2), 6.3 (D3) and 9.0 (D4) g kg^?1. Twelve 500‐L recirculating tanks were assigned to four triplicate groups with each tank stocked with 15 juveniles (39.88 ± 0.14 g) for indoor experiment. Twelve polyethylene enclosures were assigned to four groups with each one stocked with 120 juveniles (44.08 ± 1.36 g). After 8 weeks of feeding, survival ranged from 96% to 100%. Weight gain, special growth rate, protein efficiency ratio and feed conversion rate did not show significant differences among dietary treatments in both experiments. Fish cultured in the enclosures grew better, although D1 and D2 treatments did not reach significant level. Crude protein and phosphorus content of the fish were not significantly affected by dietary phosphorus level. Moisture, crude lipid, crude ash and vertebrae phosphorus were significantly affected by different phosphorus levels. Based on vertebrae phosphorus, crucian carp cultured in the tanks and in the enclosures showed phosphorus deficiency under 4.7 g kg^?1 and 6.3 g kg^?1 AP, respectively.     

Effects of dietary protein and lipid levels with different protein‐to‐energy ratios on growth performance,feed utilization and body composition of juvenile red‐spotted grouper,Epinephelus akaara

An 8‐week feeding trial was conducted to assess dietary protein and lipid levels on growth performance, feed utilization and body composition of juvenile red‐spotted grouper (7.85 ± 0.03 g fish^?1). Nine semi‐purified diets were formulated containing varying protein levels (440–520 g kg^?1, dry matter) and lipid levels (60–120 g kg^?1, dry matter). The weight gain of juvenile Epinephelus akaara was affected by dietary protein (p = .005) and its interaction with dietary lipid (p = .020). Viscerosomatic index, intraperitoneal fat ratio and whole‐body lipid level increased with increasing dietary lipid level (p < .001). Nitrogen retention was not affected by dietary protein and lipid, while lipid retention decreased with increasing dietary lipid level (p < .001). The plasma blood urea nitrogen increased with increasing dietary protein level (p = .003). This study showed that diet with 520 g kg^?1 protein and 60 g kg^?1 lipid with 30.58 mg kJ^?1 P:E provided a maximal growth for this species. Moreover, an increase in dietary lipid levels (from 60 to 90 g kg^?1) could reduce the protein requirement (from 520 to 480 g kg^?1) without affecting the growth performance, while higher fat deposition was observed in fish fed high‐lipid diets.     

Phenotypic indicators for cultured pearl size improvement in the black‐lipped pearl oyster (Pinctada margaritifera): towards selection for the recipient growth performance

The black‐lipped pearl oyster, Pinctada margaritifera, is the most important farmed species in French Polynesia and the basis of the most valuable export industry. Mass production of black pearls relies on a surgical operation requiring tissue from a donor pearl oyster to be grafted, together with a nucleus made of shell, into the gonad of a recipient oyster. Improving pearl size through family selection remains one of the main challenges for future aquaculture development. This study analyses the relative contribution of donor and recipient oysters to pearl size. To this end, hatchery‐produced donor oysters of two batches, large and small (based on shell height), were used to supply grafts for recipients, which were then monitored individually for their growth performance by recording shell height, width, and thickness, and total live weight (flesh + shells) every 6 months (four biometric measurement times) over 20 months of culture. Pearls issued from the two batches of donors showed no significant differences in nacre weight or thickness. In contrast, recipient oyster shell height and total weight were increasingly positively correlated with these pearl size parameters over the culture period, becoming significant at 8 months post‐grafting. Potential therefore exists to use shell height and oyster weight as phenotypic indicators for selective breeding of recipient oysters with high growth performance to increase pearl size in P. margaritifera.