Petit H V
Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Lennoxville QC J1M 1Z3 Canada.
J Dairy Sci. 2003 Aug;86(8):2637-46. doi: 10.3168/jds.S0022-0302(03)73859-4.
Forty midlactation Holstein cows averaging 635 kg of body weight (SE = 8) were allotted at wk 25 of lactation to ten groups of four cows blocked for similar calving dates to determine the effects of formaldehyde treatment of flaxseed and sunflower seed on fatty acid composition of blood and milk, milk yield, feed intake, and apparent digestibility. Cows were fed a total mixed diet based on grass silage and supplements for ad libitum intake over a 10-wk period. Cows within each block were assigned to one of the four isonitrogenous supplements based on either untreated whole flaxseed, formaldehyde-treated whole flaxseed, untreated whole sunflower seed, or formaldehyde-treated whole sunflower seed. Cows fed whole flaxseed compared with sunflower seed maintained greater dry matter (DM) intake (20.3 vs. 18.9 kg/d). Intake of DM, expressed as a percentage of body weight, was increased by adding formaldehyde to oilseeds (3.24 vs. 2.98%). Milk production was similar for cows fed flaxseed and those fed sunflower. Formaldehyde treatment of flaxseed and sunflower seed increased milk production by an average of 2.65 kg/d. Efficiency of fat-corrected milk yield per kilogram of DM intake was increased by formaldehyde treatment (1.31 vs. 1.21), and it was greater with sunflower seed than with flaxseed (1.33 vs.1.21). Protein concentration in milk was greater for cows fed flaxseed (3.38%) compared with those fed sunflower seed (3.21%) and formaldehyde had no effect. Apparent digestibility of DM was not affected by type of seed but it was greater for cows fed formaldehyde-treated seeds. Cows fed formaldehyde-treated flaxseed had the greatest apparent digestibilities of acid detergent and neutral detergent fiber compared with those fed the other diets. Apparent digestibilities of fatty acids were greater for sunflower seed than for flaxseed-based diets. In general, formaldehyde treatment had limited effect on milk fatty acid composition, suggesting that formaldehyde was not very effective in protecting polyunsaturated fatty acids against ruminal biohydrogenation. Feeding flaxseed resulted in the lowest omega 6 to omega 3 fatty acid ratio. The data suggest that both flaxseed and sunflower seed are acceptable fat sources for midlactating cows and that flaxseed increases milk protein percentage compared to sunflower seed.
40头处于泌乳中期的荷斯坦奶牛，平均体重635千克（标准误=8），在泌乳第25周被分配到10组，每组4头，根据产犊日期相近进行分组，以确定亚麻籽和向日葵籽经甲醛处理后对血液和牛奶脂肪酸组成、产奶量、采食量以及表观消化率的影响。奶牛在10周的时间里自由采食以青贮草和补充料为基础的全混合日粮。每个组内的奶牛被分配到四种等氮补充料中的一种，分别基于未处理的完整亚麻籽、经甲醛处理的完整亚麻籽、未处理的完整向日葵籽或经甲醛处理的完整向日葵籽。与饲喂向日葵籽的奶牛相比，饲喂完整亚麻籽的奶牛维持了更高的干物质采食量（20.3千克/天对18.9千克/天）。以体重百分比表示的干物质采食量，通过向油籽中添加甲醛而增加（3.24%对2.98%）。饲喂亚麻籽的奶牛和饲喂向日葵籽的奶牛产奶量相似。亚麻籽和向日葵籽经甲醛处理后，平均产奶量增加了2.65千克/天。每千克干物质采食量的脂肪校正奶产量效率因甲醛处理而提高（1.31对1.21），且向日葵籽组高于亚麻籽组（1.33对1.21）。饲喂亚麻籽的奶牛牛奶中的蛋白质浓度（3.38%）高于饲喂向日葵籽的奶牛（3.21%），且甲醛对此没有影响。干物质的表观消化率不受种子类型的影响，但饲喂经甲醛处理种子的奶牛表观消化率更高。与饲喂其他日粮的奶牛相比，饲喂经甲醛处理亚麻籽的奶牛酸性洗涤纤维和中性洗涤纤维的表观消化率最高。向日葵籽组脂肪酸的表观消化率高于亚麻籽组日粮。总体而言，甲醛处理对牛奶脂肪酸组成的影响有限，这表明甲醛在保护多不饱和脂肪酸免受瘤胃生物氢化方面不是很有效。饲喂亚麻籽导致ω-6与ω-3脂肪酸的比例最低。数据表明，亚麻籽和向日葵籽都是泌乳中期奶牛可接受的脂肪来源，且与向日葵籽相比，亚麻籽可提高牛奶蛋白质百分比。
