Effects of fat source in calf starter on growth performance, blood fatty acid profiles, and inflammatory markers during cold season.

This study was conducted to investigate the effects of supplementation of different fat sources in calf starters on growth performance, health, blood fatty acid profiles, and inflammatory markers during the cold season in dairy calves. A total of 48 Holstein calves (24 males and 24 females) were randomly assigned to 1 of 4 starter diets throughout the experiment (d 3 to 65): (1) no supplemented fat (CON), (2) 3% calcium-salts of soybean oil (Ca-SBO), (3) 3% calcium-salts of fish oil (Ca-FO), and (4) 3% mixture of Ca-SBO and Ca-FO (1.5% each, DM basis; MIX). Calves were given free access to starter feed and water and were raised individually in pens from 3 to 65 d of age. Calves fed Ca-SBO consumed a greater proportion of n-6 FA, while calves fed Ca-FO consumed a greater level of n-3 FA compared to the other dietary treatments. Fat supplementation increased the intake of linoleic acid, the major n-6 FA, with the greater intake observed in the Ca-SBO group compared to the other dietary treatments. Calves fed the Ca-FO and MIX diets consumed more long-chain n-3 FA than the other diets. In addition, calves fed Ca-SBO and Ca-FO diets consumed more starter feed and total dry matter than calves fed MIX and CON throughout the experiment (d 3 to 65). Calves fed Ca-FO had higher average daily gain throughout the trial (d 3 to 65) than the other treatment groups. Of all treatment groups, calves fed Ca-FO achieved the highest final body weight and showed the greatest feed efficiency. Random forest analysis revealed that eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid were the serum levels of FA most affected by the diets. The principal component analysis of blood FA profile, blood parameters, and inflammatory markers showed distinct differences between dietary treatments. Calves fed Ca-SBO had higher plasma concentrations of linoleic acid, while calves fed Ca-FO had higher plasma concentrations of long-chain n-3 polyunsaturated fatty acids (PUFA), such as EPA, docosapentaenoic acid (DPA), and DHA than the other treatment groups. Plasma inflammatory markers were lower in calves fed Ca-FO and higher in calves fed CON than in the other treatment groups. The Ca-FO group had lower levels of inflammatory markers, including serum amyloid A, tumor necrosis factor-alpha, Interferon-γ, haptoglobin, and interleukin-6 compared to the other experimental treatments. Also, the blood malondialdehyde levels, an indicator of oxidative stress, were lower in calves fed Ca-FO compared with calves fed the other treatment diets. In conclusion, the performance of preweaned dairy calves can be improved by adding fat to their starter feed under cold conditions. Overall, the type of fat in milk may affect growth and inflammation of dairy calves before weaning under cold conditions, with n-3 FA (Ca-FO) promoting growth and reducing inflammation more effectively than n-6 FA (Ca-SBO).

The effect of supplemental bioactive fatty acids on growth performance and immune function of milk-fed Holstein dairy calves during heat stress.

The present study aimed to evaluate the effects of different supplemental fat sources (soyabean oil (SBO) as a source of n-6 fatty acid (FA) and fish oil (FO) as a source of n-3 FA) in the starter feed of milk-fed dairy calves during the hot season. Forty Holstein calves (3 d of age; 39·67 kg of body weight; ten calves per group) were randomly assigned to the experimental treatments as follows: (1) starter feed supplemented with no fat source (CON), (2) starter feed supplemented with 3 % SBO (DM basis), (3) starter feed supplemented with 3 % FO (DM basis) and (4) starter feed supplemented with an equal mixture of SBO and FO (1·5 % each, DM basis). The milk feeding schedule was constant for treatments and all calves were weaned on day 65 of age. Results show that calves had greater starter intake, average daily gain and body length when fed SBO compared with the other treatments. However, feed efficiency was increased and inflammatory indicators (TNF-α, serum amyloid A and haptoglobin) concentrations were reduced in the calves fed FO compared with the other treatments. In summary, it was revealed that SBO rich in n-6 FA improved starter intake and growth performance, while FO rich in n-3 FA could improve the immune function of calves. Due to the current experimental condition, an equal mixture of SBO and FO (1·5 % each, DM basis) can be recommended to have an optimum growth performance and immune function while the calves are reared under the heat conditions.

The effects of Zinc-Methionine on glucose metabolism and insulin resistance during late pregnancy in ewes.

This study investigated the effects of dietary supplements of Zinc-Methionine (Zn-Met) on the zinc concentration of the blood and indices such as insulin resistance and glucose tolerance in late-pregnancy ewes to provide a practical solution to prevent metabolic diseases associated with energy status. In this research, 18 Makouei pregnant ewes were selected and randomized into 3 experimental groups: Group 1: Basal diet containing 10.3 mg Zn/kgDM and no zinc supplementation = CTR (Control); Group 2: Basal diet supplemented with low-dose zinc equivalent to the pregnancy requirements (30 mg Zn/kgDM) = LZN; Group 3: Basal diet supplemented with high-dose zinc (300 mg Zn/kgDM) = HZN. Blood samples for insulin resistance and glucose tolerance indices were collected according to standard methods. The results of this study indicated that supplementation of high-dose Zn-Met decreased (P < 0.05) blood glucose and tended (P < 0.1) to reduce the beta-hydroxybutyrate (BHB) concentrations. After intravenous injection of glucose and insulin, none of the glucose tolerance and insulin resistance indices were significant among groups (P > 0.05). However, the intravenous glucose tolerance test (IGTT) showed that the area under the curve (AUC) of serum glucose in the HZN group was numerically lower than that of the LZN and CTR groups. Furthermore, the numerically higher clearance rate (CR) of glucose and more negative glucose AUC following intravenous administration of insulin in Zinc-supplemented groups suggested that the ewes had greater insulin response than control group. The results showed a decrease in blood glucose concentration due to higher zinc intake after insulin injection and supported the evidence for improving insulin sensitivity. In addition, our results showed that ewes receiving zinc supplementation experienced a more favorable state of BHB or NEFA values. In conclusion, Zn-Met supplementation was found to have promising effects in improving energy metabolism in late pregnant ewes. However, further studies are needed to understand the mechanisms involved in regulating lipolysis and energy metabolism.

Influence of spray-dried rumen fluid supplementation on performance, blood metabolites and cytokines in suckling Holstein calves.

Rumen fluid from slaughtered animals is one of the wastes of slaughterhouses released to the environment that, due to its high nitrogen and phosphorus contents, can lead to soil and groundwater pollution. Meanwhile, it contains ruminal microbes and some bioactive compounds such as enzymes, minerals, vitamins and organic acids. This study was designed to examine the potential of rumen fluid as a feed additive. Therefore, the effects of spray-dried rumen fluid (SDR) with 1% maltodextrin on the performance, blood metabolites and some cytokines of sucking dairy calves during the pre-weaning phase were investigated. Forty male Holstein calves, with a mean weight of 39.4 ± 3.7 kg and 7 ± 1 days old, were randomly assigned to four groups (n = 10 calves per group) in a completely randomized design. Experimental treatments were: control diet with no additive (CON); control diet with 0.5 g/day of SDR (SDR0.5); control diet with 1 g/day of SDR (SDR1); and control diet with 1.5 g/day of SDR (SDR1.5). Daily feed intake and average daily gain of calves were not affected by feeding SDR as a feed additive. Cholesterol concentration was significantly affected by the 20th and 40th days of the experiment and decreased linearly by increasing SDR feeding level. Levels of liver enzymes, including aspartate aminotransferase and alanine aminotransferase, in the blood decreased by feeding SDR at day 40 of the experiment. Serum concentration of interleukin-6 at day 20 was not affected by dried rumen fluid feeding, whereas at day 40, a significant effect was observed among experimental treatments. The lowest value was recorded for SDR1.5 v. control calves. At day 20, the serum concentration of interferon-γ was influenced by supplementing SDR, and the highest value was recorded for SDR1.5 calves. The inclusion of SDR with 1% maltodextrin in suckling dairy calves had beneficial effects on the stimulation of calves' immune system.