Altering the ratio of dietary C16:0 and cis-9 C18:1 interacts with production level in dairy cows: Effects on production responses and energy partitioning

Abstract

The objective of our study was to evaluate the effects of altering the dietary ratio of palmitic (C16:0) and oleic (cis-9 C18:1) acids on nutrient digestibility, energy partitioning, and production responses of lactating dairy cows. Cows were blocked by milk yield and assigned to 3 groups (12 cows per group) in a main plot: low (45.2 ± 1.7 kg/d), medium (53.0 ± 1.6 kg/d), and high (60.0 ± 1.9 kg/d). Within each production group, a truncated Latin square arrangement of fatty acid (FA) treatments was used in 2 consecutive 35-d periods. The FA treatments supplemented at 1.5% of diet dry matter were (1) 80:10 (80% C16:0 + 10% cis-9 C18:1), (2) 73:17 (73% C16:0 + 17% cis-9 C18:1), (3) 66:24 (66% C16:0 + 24% cis-9 C18:1), and (4) 60:30 (60% C16:0 + 30% cis-9 C18:1). Treatment × production group interactions were observed for yields of milk, fat-corrected milk, energy-corrected milk, milk fat, milk protein, and milk lactose and energy partitioned to milk. Increasing cis-9 C18:1 in FA treatments reduced fat-corrected milk, energy-corrected milk, and milk energy output in low-producing cows but increased these in high-producing cows. Increasing cis-9 C18:1 in FA treatments did not affect milk yield, milk protein yield, and milk lactose yield in low-and medium-producing cows but increased these in high-producing cows. Regardless of production level, there was no effect of treatments on dry matter intake; however, increasing cis-9 C18:1 in FA treatments increased body weight change and body condition score change. Increasing cis-9 C18:1 in FA treatments increased total FA digestibility due to a linear increase in 16-and 18-carbon FA digestibilities. Interactions between FA treatments and production level were observed for the yield of milk fat and milk FA sources. In low-producing cows, increasing cis-9 C18:1 in FA treatments decreased milk fat yield due to a decrease in de novo and mixed milk FA without changes in preformed milk FA. In contrast, in high-producing cows, increasing cis-9 C18:1 in FA treatments increased milk fat yield due to an increase in de novo and preformed milk FA. Our results indicate that high-producing dairy cows (averaging 60 kg/d) responded better to a fat supplement containing more cis-9 C18:1, whereas low-producing cows (averaging 45 kg/d) responded better to a supplement containing more C16:0.

Use of indirect calorimetry to evaluate utilization of energy in lactating Jersey dairy cattle consuming diets with increasing inclusion of hydrolyzed feather meal

“…An increase in dietary content of cis-9 C18:1 with increasing HFM (0.85, 0.90, 0.95, and 1.01% of DM for 0HFM, 3.3HFM, 6.7MFM, and 10HFM, respectively) may have increased fatty acid digestibility. de Souza et al (2019) reported that increasing cis-9 C18:1 from 0.68 to 0.98% of diet DM linearly increased digestibility of total, 16-C, and 18-C fatty acids.…”

Effects of commercially available palmitic and stearic acid supplements on nutrient digestibility and production responses of lactating dairy cows

“…Characterization and FA profiles of the supplements are shown in Table 1. Truncated Latin square designs have been used previously in experiments in dairy science (Clark and Armentano, 1999;Weiss et al, 2013;de Souza et al, 2019a). For our truncated Latin square design with 3 × 2 treatments and periods, multiples of 12 cows were required to balance treatment sequences; therefore, each cow was assigned to 2 treatments in 2 different periods.…”

“…Research has examined the effects of feeding FA to dairy cows and differences have been reported depending on the feeding rate, production level, and FA profile (Rabiee et al, 2012). We have recently carried out research with blends of FA using commercial supplements (de Souza et al, , 2019a, but research comparing commercially available FA supplements containing different amounts of C16:0 and C18:0 is limited.…”

“…However, differences have been observed between C16:0 and C18:0 supplementation (e.g., Rico et al, 2014b;. Supplementation of C16:0 increases milk fat concentration and yield and NDF digestibility in post-peak (Piantoni et al, 2013;Mathews et al, 2016; and early-lactation cows (de Souza et al, 2019a). Rico et al (2017) fed increasing levels of a C16:0 supplement to dairy cows (from 0.75 to 2.25% diet DM) and observed positive responses on production up to 1.5% with only small decreases in FA digestibility.…”

Milk production responses to altering the dietary ratio of palmitic and oleic acids varies with production level in dairy cows

“…In post-peak cows, we recently observed that feeding a FA blend with a high content of C16:0 (80% C16:0) increased milk energy output and energy partitioning toward milk, whereas feeding a FA blend with a combination of C16:0 and cis-9 C18:1 (45% C16:0 and 35% cis-9 C18:1) increased energy allocated to BW and the partitioning of energy to BW compared with a non-fat-supplemented diet (de Souza et al, 2018). Interestingly, feeding cis-9 C18:1 not only increased BW gain in post-peak cows but also plasma insulin compared with non-FA-supplemented control diets and other FA supplements (de Souza et al, 2018(de Souza et al, , 2019. Altogether, these results suggest that C16:0 and cis-9 C18:1 are able to alter nutrient partitioning between the mammary gland and adipose tissue, which may allow for different FA supplements to be used in different situations according to the metabolic priority of dairy cows and management needs.…”