Corn processing and crude protein content in calf starter: Effects on growth performance, ruminal fermentation, and blood metabolites

Abstract

This study aimed to investigate the effects of feeding dairy calves starter diets containing corn grain processed by different methods (ground versus steam-flaked; GRC vs. SFC) and either 18% or 21% crude protein (CP) contents (dry matter basis) on growth performance, digestibility, ruminal fermentation, urinary purine derivatives, and blood metabolites of dairy calves. Holstein dairy calves (39.3 ± 1.9 kg of body weight, n = 12 calves per treatment, 6 males and 6 females) were randomly distributed to experimental diets in a 2 × 2 factorial arrangement of treatments. The 4 dietary treatments were (1) starter diet containing GRC and 18% dietary CP (GRC-18CP; geometric mean particle size, GMPS = 0.73 mm); (2) GRC and 21% dietary CP (GRC-21CP; GMPS = 0.71 mm); (3) SFC and 18% dietary CP (SFC-18CP; GMPS = 2.21 mm); and (4) SFC and 21% dietary CP (SFC-21CP; GMPS = 2.16 mm). Calves were weaned on d 63 and remained in the study until d 83 of age. The starter feed intake did not differ among treatments; however, average daily gain and feed efficiency (FE) were improved and final body weight was higher for SFC diets compared with GRC diets. The organic matter and nonfiber carbohydrate digestibilities were greater for calves fed the SFC diets than for those fed the GRC diets. The ruminal total volatile fatty acid concentrations and the molar proportions of propionate and butyrate were greater, and the molar proportion of acetate and NH 3 -N concentrations were lower, for calves fed the SFC diets than for those fed the GRC diets. The excretion of allantoin and total purine derivatives, and subsequently microbial protein synthesis, were greater for calves fed the SFC diets than the GRC diets. The total urinary nitrogen excretion and its proportion of N intake were lower for calves fed the SFC diets than the GRC diets. The blood concentrations of insulin (pre-and postweaning), glucose (postweaning), and β-hydroxybutyrate (preweaning) were greater and blood urea nitrogen (preweaning) was lower for calves fed the SFC diets than the GRC diets. The protein content of the concentrate did not affect feed intake, growth performance, or ruminal fermentation of the calves. The neutral detergent fiber digestibility was greater for calves fed the 21% CP diets than the 18% CP diets. No interaction between main effects was observed regarding the starter intake, average daily gain, body weight, FE, ruminal fermentation, and nutrient digestibility of calves. The interaction between corn grain processing and starter protein content was significant for withers and hip heights with the greatest values found for SFC-21CP treatment. Our results show that steam flaking of corn improved the organic matter and nonfiber carbohydrate digestibilities, weight gain, FE, and ruminal microbial protein synthesis, and reduced urinary nitrogen excretion compared with grinding corn. Regardless of the marginal benefit derived from feeding the diet containing SFC and 21% CP in the height of calves, lower starter protein content (18% CP) may be used efficiently ...

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

“…The measured blood metabolites were in the normal ranges found in the dairy calves (8,48,49) . The blood concentration of cholesterol was affected by the supplementation of fat.…”

“…However, some studies have noted that FO supplementation or feeding microalgal DHA in the starter diet or milk replacer reduced serum glucose and insulin levels in calves (38,39) . It can be postulated that because starch is the main influencer of blood glucose concentration in dairy calves (48) , the replacement of fat sources with a starch source (corn grain, in the current study) had the potential to reduce blood glucose concentrations thanks to the reduced ruminal propionate concentration (5,48) .…”

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

“…In addition, calves fed HI excreted more uric acid in the urine during the preweaning period. Urinary excretion PD correlates strongly with starter intake (Makizadeh et al, 2020). Thus, increased intake of starters increases the amount of organic matter available to the rumen microbiota (Clark et al, 1992), and more PD is excreted in the urine, indicating higher estimated microbial yield in the rumen.…”

“…In addition, N intake was higher in calves fed 23CP diets compared with calves fed 18CP diets (42.2 and 49.8 g/d for 18CP and 23CP diets, respectively). Accordingly, increased estimated MPS in calves fed 23CP diets (Table 5) may increase amino acid absorption in the small intestine due to higher N availability, which affects weight gain in growing calves (Makizadeh et al, 2020).…”

“…In the current study, calves fed the HI-23CP diet had the highest blood insulin levels, suggesting that high milk intake combined with high starter feed CP in the preweaning period may stimulate insulin secretion in dairy calves. Several factors have been associated with insulin secretion in young ruminants, including blood glucose concentration (Makizadeh et al, 2020), energy intake (Rastgoo et al, 2020), and small intestine ingested AA (Wester et al, 2000), all of which may be responsible for the elevated blood insulin levels on the HI-23CP diet. However, blood glucose concentrations were constant during the postweaning period between experimental treatments, although energy intake was higher for HI (6.39 vs. 5.77 Mcal/d for MOD and HI, respectively), suggesting that blood insulin concentrations in milk-fed calves are influenced by a multifactorial mechanism.…”