The distinctive short-term response of late-pregnant prolific ewes to propylene glycol or glycerol drenching.

Pregnancy toxemia is the most frequent metabolic disorder of ewes in late pregnancy. Although propylene glycol (PG) and glycerol (GLY) are common glucogenic supplements for treating pregnancy toxemia in ewes, the relative benefit of these 2 supplements is not entirely clear. Therefore, the objectives of the present study were to determine the changes during 24 h in key blood metabolites and insulin in response to PG or GLY drenching in prolific ewes. To this end, 36 multiparous late-pregnant Afec-Assaf ewes (∼132.4 d pregnant) bearing 2 to 4 fetuses, divided into 2 blocks (18 ewes in each block), with a blood ß-hydroxybutyrate (BHB) concentration of 0.5 to 1.6 mmol/L were included. Ewes were divided into 3 groups (12 ewes each; 6 ewes in each experimental day), according to their BHB levels, expected litter size, body weight, and body condition score, and were drenched with the following: (1) control group (CTL), 55 mL of water; (2) PG, 106 mL of PG (100% PG, 448 calories); or (3) GLY, 108 mL of Koforin 80 (80% GL; 448 calories). Blood samples were taken before drenching and every hour after drenching for 24 h. Plasma concentration of glucose, BHB, nonesterified fatty acids, lactate, glycerol, and insulin were determined. Because there were no effects of treatments after 12 h in the first block, the data were analyzed for 12 h after drenching rather than 24 h. The plasma glucose concentration during the first 5 h after drenching was the highest in the GLY, BHB concentration was the lowest in the PG, and the nonesterified fatty acid levels were lower in the PG compared with the CTL ewes during the first 5 h after drenching. However, glucose concentration was higher in the PG ewes at 9, 11, and 12 h after drenching than in CTL or GLY ewes. The mean lactate concentration in plasma for 12 h was 2.5- and 1.9-fold higher in the PG compared with the CTL and GLY ewes, respectively, and except at 11 h after drenching, it was significantly higher at each time point. The insulin concentration was higher in the GLY than in both other groups at 2 to 5 h after drenching. These results suggest that during the first few hours after drenching the effect of PG was more effective in reducing the BHB concentration, whereas the GLY effect was more effective in enhancing glucose concentration. The increased concentration in lactate following PG treatment suggests that the PG contribution to gluconeogenesis is mediated through its metabolism to lactate. In contrast, the lack of an effect on lactate, and the faster increase in blood glucose in response to GLY suggest that GLY has a more advanced entry point to gluconeogenesis, which influences the immediate response in enhancing the glucose blood concentration.

Saturated fat supplemented in the form of triglycerides decreased digestibility and reduced performance of dairy cows as compared to calcium salt of fatty acids.

The two most popular rumen-protected fatty acid supplements in dairy cow rations are calcium salts of palm oil fatty acid calcium salts of palm oil fatty acid (CSFA) and prilled saturated fatty acids (SFAs). The objectives of this study were to determine the effects of supplementing SFA in the form of triglycerides (TSFA), as compared to CSFA, on yields, efficiency and diet digestibility in high-yielding dairy cows. Twenty-eight (14 cows in each group) multiparous cows were fed a basal diet supplemented (on DM basis) with either 12 g/kg TSFA (~350 g/cow per day - contained 980 g/kg fat; 882.3 g/kg SFAs) or 14 g/kg CSFA (~440 g/cow per day - contained 800 g/kg fat; 566.4 g/kg SFAs). The supplement amounts in the diet were balanced according to fat content. Rumen samples were taken for measurements of ammonia and volatile fatty acids concentrations, and fecal samples were taken for digestibility measurements. The CSFA cows produced 3% higher milk yields (47.6 v. 46.2 kg/day; P < 0.0001) and 4.7% higher 4% fat-corrected milk (FCM; 44.7 v. 42.7 kg/day; P = 0.02) than the TSFA cows. No difference in milk-fat content was observed, but milk-protein content was higher in the TSFA than CSFA cows. Yields of fat and protein were similar, but lactose yields were higher in TSFA cows. There were no differences in dry matter intake or efficiency calculations between groups. The ruminal ammonia concentrations were similar between groups, whereas acetate concentrations and acetate : propionate ratio were greater for CSFA than TSFA cows. The apparent total-tract digestibility of dry (P < 0.0007) and organic matters (P < 0.0003), fat (P < 0.0001), NDF and ADF (P = 0.02) were lower in the TSFA v. CSFA cows. In conclusion, the CSFA-supplemented cows produced 3% higher milk and 4.7% higher 4% FCM than the TSFA cows. However, TSFA supplementation did not depress milk-protein content. The apparent total-tract digestibility was lower for all dietary components in the TSFA cows, which was probably due to the effects of both degree of saturation and triglyceride form of the TSFA supplement. Considering that diets were balanced according to the fat content of the supplements, the lower yields of milk and FCM observed in the TSFA than CSFA cows were likely due to the lower digestibility of the fat and other nutrients in the TSFA cows, which might have negatively influenced the dietary energy content.

Reducing milking frequency from thrice to twice daily in early lactation improves the metabolic status of high-yielding dairy cows with only minor effects on yields.

Reducing milk production during early lactation might be of interest to improve the energy balance (EB) of high-yielding dairy cows. Therefore, the objective of this study was to determine how reducing the milking frequency (MF) of high-yielding dairy cows from thrice to twice a day during the first 30 d in milk (DIM) affects yields, intake, efficiency, metabolic status, and carryover effects. To this end, 42 multiparous cows were divided into 2 groups according to their previous lactation performance, parity, and body weight. The control cows were milked 3 times a day (3ML) and the treated cows were milked twice a day (2ML) until 30 DIM and then both groups were milked 3 times a day. Milk samples were taken twice a week from 2 or 3 consecutive milkings until 45 DIM for analysis of milk solids, and both groups were followed until 100 DIM to determine the carryover effects of MF until 30 DIM. Individual dry matter intake (DMI), milk yield, and body weight were recorded daily. Blood samples were taken 3 times weekly from 14 d prepartum until 45 DIM. Milk yield during the first 30 DIM was 8.6% higher (49.3 and 45.4 kg/d, respectively), milk fat percentage was lower (3.96 and 4.27%, respectively), and the yields of all milk solids were higher in the 3ML cows than in the 2ML cows. Dry matter intake and 4% fat-corrected milk were similar between groups. The EB during the first 30 DIM was lower in the 3ML cows than in the 2ML cows, and milk yield, but not 4% fat-corrected milk yield, per unit of DMI was higher in the 3ML cows. No differences were observed between groups from 31 to 100 DIM in milk yield (∼56.3 kg/d for both groups), milk solids yield, DMI, or milk/DMI; however, fat percentage was lower and EB was higher in the 3ML cows. Blood glucose concentrations between 0 and 30 DIM were lower and ß-hydroxybutyrate concentrations were higher in the 3ML cows than in the 2ML cows, but nonesterified fatty acids concentrations were lower, which may be attributed to the lower clearance frequency of nonesterified fatty acids from the blood stream in the 2ML cows. A lower proportion of the 3ML cows (10%) ovulated ≤15 DIM compared with the 2ML cows (40%), with no beneficial effects on preovulatory follicle characteristics. Reducing the MF from thrice to twice a day during the first 30 DIM improved EB and metabolic status, with only minor effects on production.