The aim of this study was to evaluate the effect of feeding oil supplement on mammary gland development and milk production responses in Holstein cows. Ten multiparous Holstein cows (42.2±9.2 d before calving, 3.25±0.25 body condition score, and 620±35 kg body weight) were randomly assigned to treatments. Treatments were a diet with oil added as palm oil (PO; n=5), or fish oil (FO; n=5) given to cows until 63 d in milk. Milk yield was recorded daily, milk composition (fat, protein, lactose, total solid and somatic cell count) was measured weekly and fatty acid profiles of milk fat were determined at first and last week of the experiment. Samples of mammary tissue were obtained at 7 and 63 d in milk by biopsy gun. Tissue slides were analyzed by Image J software. Results showed that fish oil supplemented diet compared to the palm oil supplemented diet increased milk production after 6 weeks of lactation (P<0.05), content of polyunsaturated fatty acids milk fat (P<0.05) and docosahexaenoic acid (P<0.01). Moreover, n-6:n-3 ratio was decreased by fish oil supplement (P<0.05). Histological studies showed that FO increased the relative percentage of tissue area occupied by epithelial cells as well as a number of total alveoli in each microscopic field (P<0.05). Data suggested that feeding fish oil during the dry period and early lactation could improve development and function of the mammary gland in the dairy cow.
Background
The second half of the first pregnancy is a critical period in the growth and development of the mammary gland. The use of functional compounds during this period may positively impact livestock performance.
Objectives
In this study, changes in lipogenic enzyme gene expression in the mammary gland of Saanen goats in response to different dietary fat sources were analysed.
Methods
Goats from four groups (10 each) received these diets from the last two months of pregnancy through four months of lactation: C−, no added fat (negative control group), C+, with saturated palm oil (positive control group), SB, with roasted soybeans (omega‐6 group) and FS, with extruded flaxseed (omega‐3 group). The fat content was about 4% of dry matter. Milk yield, milk fatty acid profile, milk health index (HI) and gene expression of four lipogenic enzymes in mammary tissue were measured.
Results
The FS group had significantly higher milk production with lower omega‐6 to omega‐3, monounsaturated to polyunsaturated, and total saturated fatty acids compared to other groups. The shorter and longer than16‐carbon chain of total milk fatty acid indicates significantly higher values for the C− and C+ groups, respectively. The milk HI for the SB group was significantly higher. The gene expression profile for acetyl‐coenzyme A carboxylase was higher in the C− group than other experimental groups.
Conclusions
The results show that manipulation of the diet with unsaturated fat supplements improved milk production, synthesis of milk fat and molecular expression of lipogenic enzymes in mammary tissue in primiparous Saanen goats.
A wide variety of comparative performance reports from use of different levels of dietary supplements in animal production can be helpful to decision makers. However, with the complexity and amount of information in these reports, decision making as to which dietary level of supplement is to be used is difficult. This problem is overcome only when all data can be put into a common unit. For this purpose, the present study examined our previously reported data on the effects of different levels of dietary Saccharomyces cerevisiae on performance and egg quality traits of laying hens. In this survey, five different scoring methods of maximin, equally likely, weighted average, ordered weighted averages and technique for order preference by similarity to ideal solution (TOPSIS) were used to choose the best level (0, 0.25, 0.5, 0.75 and 1 g kg -1 diet) of dietary Saccharomyces cerevisiae. The methods of equally likely, weighted average, and ordered weighted averages showed the best result at 1 g kg -1 diet of the dietary supplement but maximin and TOPSIS showed only 0.5 and 0.75 of dietary level, respectively. Overall, birds fed diet containing 0.75-1 g yeast per kg diet had better performance as compared to other groups.
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