Rising food security concerns are driving the livestock sector to explore alternatives to cereal grains, like by-products from the food industry, but their effect on animals needs to be studied. The study assessed the impact of replacing 55% cereal grains with former food products (FFP) on ruminal fermentation, ruminal methane production, and blood metabolites, with or without cocoa bean shell (CBS) supplementation. We conducted a first (spring, E1) and a second (fall, E2) experiment, each with 17 early-lactating Holstein and Red Holstein cows. Each experiment lasted 6 weeks, including a 3-week adaptation and a 3-week experimental period. In each experiment, the animals were fed freshly cut grass as a basal diet and were balanced for milk yield, parity, and days in milk and assigned to three concentrate types (CCT): (i) a control concentrate (CON), (ii) a concentrate consisting of 55% FFP (FFP-), and (iii) an FFP concentrate that included an additional 5% CBS (FFP+ ). Feed intake and milk production were recorded daily during the 3-week sampling period; blood serum and ruminal fluid samples were collected twice, at the end of the adaptation and experimental periods. Statistical analyses were conducted on data from both experiments. DM, herbage, and most nutrient intakes were greater in E2 than in E1, probably because of seasonal changes in herbage quality. In E1, CON cows had lower DM intake (DMI) than FFP- cows, whereas in E2, CON cows had greater DMI than FFP+ cows. Across experiments, FFP- and FFP+ cows had greater water-soluble carbohydrates and fat and lower starch intakes than CON cows. The energy-corrected milk yield was greater in E1 than in E2 and unaffected by CCT. Irrespective of the experiment, the CON cows had the greatest, FFP- intermediate and FFP+ lowest milk lactose percentages and FFP+ cows had greater milk fat percentages than CON cows. The mean and maximum reticular pH were lower for CON than for FFP- cows in E1 and were unaffected by CCT in E2. Irrespective of the experiment, acetate proportions in ruminal fluid of CON cows were lower than those of FFP- and FFP+ cows. Methane yield was greater in E2 than in E1 and unaffected by CCT. Serum albumin, non-esterified fatty acids and glucose levels varied by CCT in E2, but not in E1. Combining FFP and CBS with herbage could help increase the sustainability of early-lactating dairy cow nutrition without compromising health, but results need future corroboration.

In the present experiment, 10 horned and 10 disbudded mid-lactating Brown Swiss cows were included in a crossover feeding trial with a hay or hay and concentrate diet. The effects of dietary neutral detergent fiber (NDF) content and horn status on thermoregulatory responses under thermoneutral and short-term heat stress conditions were studied, as both are considered to ease the cow's thermoregulation under an environmental heat load. Cows received either ad libitum hay and alfalfa pellets (85:15, C-, NDF content: 41.0%) or restricted amounts of hay and concentrate (70:30, C+, NDF content: 34.5%). The level of restriction applied with the C+ diet was determined from pre-experimental ad libitum intakes, ensuring that both diets provided the same intake of net energy for lactation (NE_L). For data collection, cows were housed in respiration chambers for 5 d. The climatic conditions were 10°C and 60% relative humidity (RH), considered thermoneutral (TN) conditions (temperature-humidity index (THI): 52) for d 1 and 2, and 25°C and 70% RH, considered heat stress (HS) conditions (THI: 74), for d 4 and 5. On d 3, the temperature and RH were increased gradually. Compared with TN, HS conditions increased the water intake, skin temperature, respiration and heart rates, and endogenous heat production. They did not affect body temperature, feed intake, or milk production. Lowering dietary fiber content via concentrate supplementation lowered methane and increased carbon dioxide production. It did not mitigate physiological responses to HS. Although the responses of horned and disbudded cows were generally similar, the slower respiration rates of horned cows under HS conditions indicate a possible, albeit minor, role of the horn in thermoregulation. In conclusion, future investigations on nutritional strategies must be conducted to mitigate mild heat stress.

The effect of the horn status of cows on their milk composition and quality is a controversial research topic. In this study, 128 milk samples from 64 horned and 64 disbudded Brown Swiss and Original Braunvieh cows were collected from alpine farms where both horned and disbudded cows were grazing on mountain pastures. The samples were analyzed for their detailed composition and protein digestion in a simulated in vitro digestion (INFOGEST). To exclude probable influences on digestion, the (3-CN genotype with its variants A1 and A2 was also included in the study. The effects of horn status and (3-CN genotype were investigated in linear mixed models, which included additional influencing random factors such as Original Braunvieh blood proportion, stage of lactation, and farm. Horn status did not have any effect on milk composition or digestion. In contrast, milk from A1 A1 cows showed a different protein digestion than milk of A1A2 and A2A2 cows in the gastric phase, including smaller amounts of (3-casomorphin(BCM)21-associated peptides and larger amounts of BCM11-associated peptides. Abundances of BCM7 did not differ between (3-CN genotypes. At the end of the intestinal phase, the digested milk of A1A1 and A2A2 (3-CN genotypes did not differ.

Summary: We investigated exhaled breath to explore potential new biomarkers for the energy balance (EB) of dairy cows fed fresh herbage. Cows (n = 19) exhibiting negative (lactation week 5) and positive (lactation week 10) EB differed in their exhaled-breath profiles, namely in certain exhaled volatile organic compounds (VOC). The most discriminating exhaled VOC were the fatty aldehydes octanal, nonanal, and decanal. These VOC and serum β-hydroxybutyrate (BHB) and nonesterified fatty acids (NEFA) correlated with the calculated EB in 32 cows. Thus, exhaled fatty aldehydes could be considered in assessing the energy status of dairy cows.