Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA.
Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907, USA.
J Anim Sci. 2024 Jan 3;102. doi: 10.1093/jas/skae282.
Fat supplementation has potential to improve reproductive performance and increase pregnancy rates in cattle by increasing the energy density of the diet. However, some of the positive effects of fat seem to be influenced by the type of fatty acid fed. Docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) are long-chain n-3 poly-unsaturated fatty acids (PUFA) that have important biological effects on reproduction through their involvement in hormone and series 3 prostaglandin synthesis. Ruminant tissues are naturally almost devoid of n-3 long-chain PUFA, specifically EPA and DHA. Algae biomass provides a consistent source of DHA and EPA that could be fed to alter hormonal profiles and improve reproduction of beef heifers. Eighty-eight Angus × Simmental heifers (427 ± 1.8 kg body weight [BW]) were blocked by BW and allotted to 2 treatments (44/treatment, 4 pens/treatment, 11 heifers/pen). Control heifers were fed a diet that contained (dry matter [DM] basis) 52.8% mixed grass silage, 32% corn silage, and 15.2% concentrate. DHAgold (49% fat; 21.8% DHA; DSM Inc.) was included in the algae diet at 1.65% DM, replacing equal parts of corn and DDGS. Diets were formulated to contain 12% crude protein and 0.85 Mcal/kg net energy for gain (NEg). Heifers were fed treatment diets from 54 d prior to the breeding season through the first trimester. Follicular fluid was collected on day 47 for hormonal analysis. Artificial insemination (AI) was from days 54 to 77. Heifers that did not get pregnant to AI were removed from the study on day 109 and placed with a bull. The study ended on day 180. Data were analyzed using the MIXED procedure of SAS. During the pre-breeding period, algae heifers had lesser dry matter intake (P = 0.006) compared to control heifers. Heifers supplemented with algae had a greater average daily gain (P = 0.03) during the breeding period and BW tended (P = 0.06) to be greater for algae compared to control heifers on day 98 and was greater on day 180 (P = 0.03). Dominant follicle diameter and follicular estrogen concentration were unaffected by treatment (P ≥ 0.12). Follicular insulin-like growth factor-1 was greater in algae compared to control heifers (P = 0.03). First service conception rate did not differ between treatments (P = 0.67); however, second service and overall conception were lesser (P ≤ 0.03) in algae compared to control heifers. These data suggest supplementing DHA-rich algae improved growth but decreased conception rates of primiparous beef females.
脂肪补充剂通过增加日粮的能量密度，有可能改善牛的繁殖性能并提高受孕率。然而，脂肪的一些积极作用似乎受到所喂养的脂肪酸类型的影响。二十二碳六烯酸（DHA，22：6n-3）和二十碳五烯酸（EPA，20：5n-3）是长链 n-3 多不饱和脂肪酸（PUFA），通过参与激素和 3 系列前列腺素的合成，对繁殖具有重要的生物学作用。反刍动物组织中天然几乎不含 n-3 长链 PUFA，特别是 EPA 和 DHA。藻类生物量提供了一种一致的 DHA 和 EPA 来源，可以通过喂养来改变激素谱并提高肉牛小母牛的繁殖能力。88 头安格斯×西门塔尔小母牛（427±1.8 公斤体重[BW]）按 BW 分组，分为 2 个处理组（每组 44 头，每组 4 个围栏，每个围栏 11 头小母牛）。对照组小母牛饲喂含有（干物质[DM]基础）52.8%混合草青贮、32%玉米青贮和 15.2%浓缩饲料的日粮。DHAgold（49%脂肪；21.8% DHA；DSM Inc.）以 1.65% DM 的比例包含在藻类日粮中，取代了等量的玉米和 DDGS。日粮配方含有 12%粗蛋白和 0.85 Mcal/kg 净能增重（NEg）。小母牛在配种前 54 天至第一孕期开始饲喂处理日粮。在第 47 天收集卵泡液进行激素分析。人工授精（AI）从第 54 天到第 77 天进行。未通过 AI 怀孕的小母牛在第 109 天被从研究中移出，并与公牛一起饲养。研究于第 180 天结束。数据采用 SAS 的 MIXED 程序进行分析。在配种前期间，藻类小母牛的干物质摄入量较少（P=0.006）。在配种期间，补充藻类的小母牛的平均日增重更大（P=0.03），并且在第 98 天和第 180 天，藻类组的 BW 倾向于（P=0.06）大于对照组（P=0.03）。优势卵泡直径和卵泡雌激素浓度不受处理影响（P≥0.12）。与对照组相比，藻类组的卵泡胰岛素样生长因子-1更高（P=0.03）。初配受孕率两组之间无差异（P=0.67）；然而，在藻类组中，第二次配种和总受孕率较低（P≤0.03）。这些数据表明，补充富含 DHA 的藻类可以提高初产肉牛小母牛的生长速度，但会降低受孕率。
