The Effect of Using Different Fat Sources in Close-Up Diets on the Feed Consumption, Blood Parameters, Body Measurements and Performance of Holstein Dairy Calves

 Raising healthy calves is indeed a critical concern in the dairy industry. Close up diets have important effects on the quantity and quality of produced colostrum, on the other hand, colostrum and milk are considered the most important sources of food that contain energy, protein, and other nutrients for the newborn calf’s growth. Including fatty acids in the late pregnancy supplements are controversial because of the potential reduction of cows DMI. Also, the growth and health of calves can be influenced by feeding linoleic acid to pregnant cows. Safflower as a rich source of linoleic acid (55-70%) is a significant oil alternative product, and has a high nutritional value. This study aimed to examine the effects of safflower seeds and palmitic fatty acids on the transition diet in cow feed consumption, colostrum quality, blood parameters, body measurements and Holstein calf performance.

Materials and methods :

Thirty pregnant Holstein cows, 15 primiparous and 15 multiparous, were used 21 days prior to the expected calving date. The experiment was conducted using a completely randomized experimental design with three treatments and ten replicates in every treatment. Cows were randomly assigned to experimental treatments so that each treatment have an average body weight 659.34 ± 84.2 kg, parity 2.04 ± 1.31 and body condition score (BCS) 3.23 ± 0.15 The experimental rations have similar energy and protein content. Diets were thoroughly mixed and fed to cows based on the recommendations of the US National Research Council (NRC, 2001). The experimental rations included: 1) Control diet without fat source (Ctrl), 2) Diet with palmitic fatty acid (SFA), and 3) Diet with safflower seed (UFA). Daily feed intake was calculated by subtracting distributed feed to every cow from the leftover amount on following day. Newborn calves were weighed immediately after birth. An individual colostrum yield for every cow was recorded at each milking. The quality of colostrum was determined using an optical refractometer (ATC., China). The body weight and skeletal parameters of calves were evaluated at birth day, 21 d, and 49 d. Blood samples were taken immediately after birth, two hours after colostrum feeding and on days 3, 7, 21, and 49 via the jugular vein. Samples were centrifuged at 3000× g and the plasma was stored at −20°C until analysis. Plasma metabolites were analyzed using an autoanalyzer (Alcyon 300., USA). Colostrum composition (fat, protein, lactose, solids, solids not fat) was determined using a Milkoscan (Foss Electric, Hillerød, Denmark). Fatty acids profile were measured according to O'Fallon (2007) et al., using gas chromatography (GC) equipped FID detector and 100 meter column. Data were analyzed using the MIXED procedure of SAS using a completely randomized design with ten replications.

  Results and Discussion:

 Using sources of SFA (palm oil powder) and UFA (safflower seeds) in the transition diets were not affected on dry matter intake in Holstein dairy cows (P>0.05). Dry matter intake in Ctrl, SFA, and UFA were 10.29, 10.98, and 10.80 kg per day, respectively. We found that  using SFA and UFA did not have any significant effect on colostrum parameters such as colostrum volume, the percentage of fat, protein, lactose, total solids, fat not solids, and also, immunoglobulin concentration, and Brix number of colostrum (P>0.05). The colostrum volume in UFA and SFA treatments was higher than in the Ctrl treatment, but this difference was not significant (5.82, 5.23, and 4.19 kg, respectively). According to the results, the researchers stated that adding raw and processed safflower seeds to the diet did not have any significant effect on milk production, milk fat, protein, and lactose in Holstein dairy cows (Paya and Taghizadeh, 2020). Feeding omega-6 sources in the transition period (35 days before calving) caused higher colostrum protein and Brix values (Salehi et al., 2016) but was not consistent with our results. Feeding palm fat powder as a source of SFA and safflower seeds as UFA did not have any significant differences in concentration of short chain, medium chain, and long chain fatty acids in colostrum. It was reported that various fat sources in the rations of dairy and transition cows did not affect colostrum fatty acid and milk fatty acid. However some studies showed that different fat sources in the diet of dairy cows changed the fatty acid profile in milk. In general, it can be stated that because of the high-producing dairy cows experience a negative energy around calving, the diet energy meets the requirements, which probably causes the fatty acid composition of the colostrum not to be affected. Our results showed that blood factors such as glucose, cholesterol, triglycerides, blood urea nitrogen, ALT, AST, total antioxidant capacity, malondialdehyde, total protein, albumin, calcium, magnesium, phosphorus, and HDL did not differ between treatments. It was observed that the addition of SFA and UFA had no significant effect on the birth weight of calves, weight at d 21 and 49, and dry matter intake during the experimental period. Skeletal parameters such as hip height and width, withers height, chest circumference, and body length at 3, 21, and 49 days had no significant differences in the treatments.

  Conclusion:

 It seems that using saturated and unsaturated fatty acids sources in the transition diets did not reduce feed intake. Moreover, it had no significant influence on the calves' performance, bone condition, the colostrum's quality and the colostrum fatty acids profile.