Soybean oil supplementation and starter protein content: Effects on growth performance, digestibility, ruminal fermentation, and urinary purine derivatives of Holstein dairy calves

Abstract

This study investigated the effects of feeding dairy calves starter diets containing 19% or 22% crude protein (CP) content on a dry matter basis and either supplemented or not with soybean oil (SBO, 0 vs. 3%, dry matter basis) on growth performance, digestibility, urinary nitrogen, and purine derivatives (PD) excretion. A total of 48 female Holstein dairy calves (mean 39.8 kg of body weight) were randomly distributed to experimental diets in a 2 × 2 factorial arrangement of treatments. The 4 dietary treatments were (1) starter diet without SBO supplement and 19% CP (NSBO-19CP), (2) starter diet without SBO supplement and 22% CP (NSBO-22CP), (3) starter diet with 3% SBO and 19% CP (SBO-19CP), and (4) starter diet with 3% SBO and 22% CP (SBO-22CP). Milk feeding value was similarly based on a constant protocol across experimental treatments and calves had ad libitum access to water and starter diets throughout the study. All calves were weaned on d 63 of age and remained in the study until d 83 of age. Calves supplemented with SBO had lower starter feed intake and average daily gain (ADG) and lower feed efficiency (FE) but had a higher fecal score indicating a higher likelihood of diarrhea occurrence compared with unsupplemented calves. Wither heights, digestibilities of organic matter, CP, and neutral detergent fiber were decreased, and ruminal volatile fatty acids tended to be reduced, and the molar proportion of ruminal butyrate (preweaning) and acetate (postweaning) reduced by supplemental SBO. The urinary allantoin and total PD excretion were reduced; however, urinary nitrogen excretion was increased when calves were supplemented with SBO.The CP amount did not affect starter feed intake, FE, or diarrhea occurrence rate, whereas the 22CP diets increased neutral detergent fiber digestibility, improved ADG (tendency), and increased allantoin and urinary PD excretion compared with the 19CP diets. The starter feed intake, ADG, FE, diarrhea occurrence rate, nutrient digestibility, and ruminal fermentation were not affected by the interaction between starter SBO and CP level; however, hip height and total PD in calves that received the SBO-22CP diets were higher than those fed the SBO-19CP diets. In conclusion, based on our experimental conditions, supplemental SBO could not be recommended for dairy calves. Furthermore, our findings indicate that SBO has negative effects on performance more attributed to reducing starter intake, digestibility, and ruminal volatile fatty acid concentration rather than because of a limitation of starter metabolizable protein supply and intestinal amino acid availability. Therefore, our results indicate that feeding the higher starter CP content is not a viable strategy to compensate for the negative effects of SBO supplementation on the growth performance of dairy calves.

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

“…It seems that the lower ADG in FO-fed calves is mostly related to lower starter intake, as observed in the present study or the above-mentioned studies. However, it is notable that environmental conditions (heat stress, cold stress and thermo-neutral conditions) and method of oil delivery (mixed with milk replacer or mixed with a starter such as Ca salt) can also influence the obtained results (5,6) .…”

“…Generally, carbohydrates prepare the primary source of energy in starter diets for young calves. Although some research indicated negative effects of supplemental fat on dairy calf growth performance, this was mainly due to the detrimental effects of fat on nutrient digestibility, ruminal fermentation and microbial activity (5,6) ; however, positive results have been obtained when calves received different supplemental fat, such as essential fatty acid (FA) (7) or n-3 FA, supplied through linseed oil (LSO) in starter diets (8) . Discrepancies among studies that have evaluated fat incorporation in calves' diets can be related to many factors, such as fat feeding levels, fat delivery methods through a liquid or solid feed, starter processing methods or individual FA profiles of the supplemented fat (2) .…”

“…The high ruminal availability of supplemental FA for rumen microbes can reduce microbial activity, microbial protein synthesis, fibre digestibility and even looser faecal score that can cause a high diarrhoea rate in milk-fed calves (5) . This can be more detrimental when calves are supplemented with ruminally unprotected unsaturated FA (UFA) (5,6) that can mask the favourable effects of the UFA. Saponification of FA with Ca salts is a strategy used to reduce the ruminal availability of supplemental FA for rumen microbes.…”

“…The minor replacement of coconut oil with porcine lard in milk replacer increases the intake of linoleic and α-linolenic acids and can improve calf growth performance and some facet of immunity (10) . Dairy calves suffer from diarrhoea in the early weeks of life due to the low immune function and their high susceptibility to pathogens, and this is more obvious in dairy farms during hot conditions (1,6,12) . Thus, we assumed that a greater n-3:n-6 FA ratio in starter feed of dairy calves may improve the immunity of animals under hot conductions.…”

Milk feeding level and starter protein content: Effects on growth performance, blood metabolites, and urinary purine derivatives of Holstein dairy calves

“…We suspected that the level of milk feeding may influence estimated microbial growth through factors such as intake of starters and changing the ratio CP:ME. In addition, bovine milk contains purines (Gonzalez-Ronquillo et al, 2003), which may affect the results of estimated microbial yield from urinary purine derivatives (PD) in milkfed dairy calves (Yousefinejad et al, 2021), which has not been considered thus far for different milk feeding levels. Funaba et al (1995) evaluated urinary excretion of PD immediately after weaning and indicated that urinary excretion of PD was atypical 1 wk after weaning, compared with calves at 6 wk of age.…”