Effects of replacing alfalfa hay with Lycium barbarum branch on milk performance, nutrient digestibility, and ruminal fermentation in Holstein dairy cows

Use of unconventional feeds is an important way to solve the shortage of traditional forage resources in dairy production. This study evaluated the effects of replacing alfalfa hay with Lycium barbarum branches (LBB) in dairy cow diets on the lactation performance, milk fatty acid (FA) composition, nutrient digestibility, rumen fermentation, and blood metabolites. Forty-five midlactation Holstein cows with a milk yield of 26.5 ± 8.37 kg/d and parity of 2.1 ± 0.37 were assigned to a randomized complete block design to 3 groups: 0LBB, 50LBB and 100LBB, with LBB replacing 0%, 50%, and 100%, respectively, of alfalfa hay in cow diet (on a DM basis). The study lasted for 75 d (15-d adaptation + 60-d treatment). Results showed that replacing alfalfa hay with LBB did not affect DMI and feed efficiency. When compared with cows receiving 0LBB, those on the 100LBB treatment had a higher yield of 4% FCM (32.5 kg/d vs. 29.9 kg/d) and protein (1.12 kg/d vs. 1.01 kg/d), and cows on 50LBB or 100LBB had a greater milk fat yield and content. The total de novo FA proportion in milk fat was higher in cows fed 50LBB (31.5%) or 100LBB (32.2%) than 0LBB (30.7%). The total PUFA was higher in 100LBB (4.81%) compared with the 0LBB (4.63%) or 50LBB (4.66%) treatments. However, the proportion of mixed FA (C16), preformed FA, SFA, and MUFA in milk fat did not change significantly with LBB inclusion. When compared with cows receiving 0LBB, cows fed 50LBB or 100LBB had a higher whole-tract digestibility of DM and OM, and those fed 100LBB had a higher whole-tract digestibility of ADF, NDF, and CP. Rumen fluid pH was lower, but the contents of total VFA, acetate, propionate, and butyrate were higher, and acetate molar proportion and acetate-to-propionate ratio and ammonia N were lower in cows receiving 100LBB compared with 0LBB. Compared with 0LBB, cows receiving 100LBB had a greater albumin content and superoxide dismutase and total antioxidant capacity activities in blood. The results indicated that replacing alfalfa hay with LBB improved the performance, apparent nutrient digestibility, ruminal fermentation, and antioxidant capacity in lactating Holstein cows.