Reduction of crude protein in diets fed to lactating Holstein-Gyr cows

Abstract

The objective of this work was to evaluate the effect of reducing crude protein (CP) contents in diets with a constant metabolizable protein content on the intake, performance, nitrogen balance, and nutrient digestibility of lactating Holstein-Gyr cows. Animals (n = 24, 103±23 days in milk) were allocated to four treatments (n = 6 per group) with different CP contents: 127, 132, 139, and 156 g kg-1 dry matter (DM). DM intake was not affected by treatments. CP intake and digestibility increased linearly with higher CP contents. Milk yield (23.7±3 kg per day) and the percentages of milk protein (3.3±0.2%) and fat (3.8±0.5%) were not affected by CP reduction. Milk and blood urea nitrogen increased linearly with the increase of CP in the diet, similarly to urinary nitrogen excretion. Nitrogen use efficiency was 29.8 and 22.4% when CP was 127 and 156 g kg-1 DM, respectively. Reducing CP in diets fed to mid-lactating Holstein-Gyr cows increases nitrogen use efficiency and maintains the productive performance of the cows.

Diet crude protein reduction on follicular fluid and cumulus-oocyte complexes of mid-lactating Girolando cows

“…Despite the CP reduction in their diets, all the mid-lactating Girolando cows in this study were able to intestinally absorb the same amount of protein once the diets were balanced to supply the same metabolizable protein between the groups. Additionally, as shown in our previous paper (Guimarães et al, 2018), the reduction of CP resulted in improved nitrogen efficiency, thus, reducing urinary nitrogen excretion and milk urea nitrogen, without altering the DMI and milk production.…”

“…The experiment was approved by Embrapa Dairy Cattle (protocol number 14/2014) and was conducted on the corporation's experimental farm, located in Coronel Pacheco, Minas Gerais, Brazil. The experiment's nutritional design is further detailed in Guimarães et al (2018). Twenty-two mid-lactating Girolando cows (ten 3/4 Holstein and twelve 7/8 Holstein, Table 1), 15 primiparous and seven multiparous, with 21.55 ±3.19 L/day daily milk production, 105.30 ± 22.62 days in lactation, 3.22 ±0.03 body condition score, and 475.8 ±7.75 Kg body weight, were used for this trial.…”

“…A soybean meal treated with lignosulfonates that prevent microbial fermentation (SoyPass ® , Cargill ® , Uberlândia, Brazil) was used to substitute the urea and soybean meal in the diet formulation to increase RUP (Table 2). The effect of the diets' CP reduction on DMI, digestibility, milk yield, and nitrogen efficiency parameters of this trial are broadly outlined and discussed in Guimarães et al (2018). To measure urea-N, glucose, and non-esterified fatty acid concentrations (NEFA), blood and follicular fluid samples were harvested 22, 38, 52, and 68 days after the beginning of the experimental diets.…”

The Dairy Cow Slurry Composition Used as Organic Fertilizer Is Influenced by the Level and Origin of the Dietary Protein

“…The nitrogen efficiency is more than three percentage points higher in the low protein treatment than the medium and high protein treatments because the ingestion of N was also lower in the low protein treatment. Several studies have reported that the nitrogen efficiency rises when on a low-protein diet and falls when on a high-protein diet and maintaining the milk yield [21,46]. In the second trial, the nitrogen efficiency was lower than that seen in the LP treatment of the first trial and similar to HP and MP treatments.…”

Effects of <i>Stylosanthes scabra</i> Forage Supplementation on <i>in Vitro</i> Gas Production and Fiber Degradation of <i>Eragrostis</i> Grass Hay

“…Contrariwise, the CP value of Stylosanthes scabra accessions at maturity was above 170 g/kg, and that shows that Stylosanthes scabra forages can be used as protein source for low-quality forage. In fact, the CP value of the Stylosanthes scabra accessions was adequate for lactating dairy cows [51]. The NDF in the other hand was below the range of 60% to 65% that is reported to depress feed intake due to low digestibility [18] [50].…”