The rumen is a complex ecosystem that plays a critical role in our efforts to improve feed efficiency of cattle and reduce their environmental impacts. Sequencing of the 16S rRNA gene provides a powerful tool to survey the bacterial and some archaeal. Oral stomach tubing a cow to collect a rumen sample is a rapid, cost-effective alternative to rumen cannulation for acquiring rumen samples. In this study, we determined how sampling method (oral stomach tubing vs cannulated grab sample), as well as rumen fraction type (liquid vs solid), bias the bacterial and archaeal communities observed. Liquid samples were further divided into liquid strained through cheesecloth and unstrained. Fecal samples were also collected to determine how these differed from the rumen sample types. The abundance of major archaeal communities was not different at the family level in samples acquired via rumen cannula or stomach tube. In contrast to the stable archaeal communities across sample type, the bacterial order WCHB1-41 (phylum Kiritimatiellaeota) was enriched in both liquid strained and unstrained samples as well as the family Prevotellaceae as compared to grab samples. However, these liquid samples had significantly lower abundance of Lachnospiraceae compared with grab samples. Solid samples strained of rumen liquid most closely resembled the grab samples containing both rumen liquid and solid particles obtained directly from the rumen cannula; therefore, inclusion of particulate matter is important for an accurate representation of the rumen bacteria. Stomach tube samples were the most variable and were most representative of the liquid phase. In comparison with a grab sample, stomach tube samples had significantly lower abundance of Lachnospiraceae, Fibrobacter and Treponema. Fecal samples did not reflect the community composition of the rumen, as fecal samples had significantly higher relative abundance of Ruminococcaceae and significantly lower relative abundance of Lachnospiraceae compared with grab samples.

Modification of milk fat composition might be a desirable method to alter manufacturing characteristics or produce dairy products low in saturated fat that more closely meet consumer dietary preferences. The aim of this research was to evaluate functional properties of cream obtained from milks with fat composition modified by altering the profile of long-chain fatty acids (FA) absorbed from the intestine. A control and 5 mixtures of long-chain free FA were infused into the abomasum of lactating dairy cows in a 6 × 6 Latin square design with 21-d periods. Treatments were as follows: (1) control (no FA infused), (2) mostly saturated FA (C16:C18 = 0.74), (3) low linoleic palm FA (C16:C18 = 0.73), (4) palm FA (C16:C18 = 0.73), (5) soy FA (C16:C18 = 0.10), and (6) high palmitic soy FA (C16:C18 = 0.73). All treatments included meat solubles and Tween 80 as emulsifiers. Viscosity, overrun, whipping time, foam firmness, and foam stability were evaluated in creams (33% fat). Cream from cows infused with soy FA (treatment 5) had the longest whipping time and lowest overrun, foam stability, viscosity, melting point, firmness, and solid fat content at 5 and 20°C because the fat had the highest unsaturated FA content. Increasing palmitic acid content of soy FA (treatment 6) improved functional variables in cream relative to soy FA alone. Differences among treatments 1 to 4 were less pronounced because of the effect of C18:1 trans in treatments 3 and 4 on milk fat yield and composition. Milk fat from cows infused with palm FA (treatment 4) exhibited comparable or better functionality than control cream. Increased polyunsaturated FA in milk fat resulted in increased amounts of triglyceride (TG) fractions with 28, 30, 38, and 40 carbon numbers, increased oleic acid resulted in increased 50-carbon TG, and higher palmitic and myristic acids resulted in greater 44, 46, and 48 carbon number TG. These TG groups consistently correlated with functional properties of creams from different treatments. Our results indicated that optimal functionality of cream is dependent more on its content of palmitic acid than on unsaturated FA. However, an optimal composition of milk fat for cream functional characteristics might be obtained through nutritional manipulation of diets for dairy cows to deliver an optimal profile of FA.

Abstract The aim of this study was to determine the in vitro digestibility and in sacco disappearance of dry matter (DM) and neutral detergent fibre (NDF) in total almond hulls (TAH), pure almond hulls (PAH) or Debris. The TAH were used because there are no data on the effect of debris (non-hull material) on the nutritional value of almond hulls. Twelve samples of commercial almond hulls were used, with one subsample representing the TAH and the other subsample hand sorted to separate the hulls (PAH) from Debris. Gas production and Ankom Daisy method were used to determine in vitro digestibility, while two rumen-fistulated cows were used to measure in sacco disappearance of PAH and TAH. For in vitro digestibility, both PAH and TAH were more digestible and had greater gas production than Debris. The PAH had greater in vitro true digestibility on a DM basis and NDF digestibility at 48 and 72 h compared with TAH. Nonpareil hulls provided greater metabolizable energy (ME) concentration when compared with other almond varieties, with PAH supplying numerically more ME than TAH for both varieties. For in sacco disappearance, PAH had greater DM and NDF disappearance along with a greater rate of disappearance for NDF compared with TAH. This research demonstrated that Debris is highly indigestible; therefore, hulling, agronomic and harvesting practices should be focused on reducing Debris in commercial almond hulls to improve their nutritive value as a feedstuff for livestock.

California is the leading state for the production of almonds, with more than 400,000 bearing hectares of orchards that produced approximately 1 billion kilograms of shelled nuts in 2017. Almond hulls (AH) are a regional by-product feedstuff fed predominantly to dairy cattle in California. A 2012 study surveyed 40 dairy farms in California and found that 39 out of 104 total mixed rations contained AH, with a mean daily feeding rate of 1.45 kg/cow. In 2017, approximately 2 billion kilograms of AH was produced. At a feeding rate of 1.45 kg/cow daily, even if all 1.7 million lactating cows in California are consuming AH, there will be a surplus of AH on the market as the approximately 130,000 nonbearing hectares come into nut production. Therefore, the potential of feeding varying amounts of AH to lactating dairy cows was investigated using 12 Holstein cows with 4 primiparous and 8 multiparous cows. The dietary treatments were 4 total mixed rations containing 0, 7, 13, or 20% AH. The AH used contained 12.8% crude fiber (as-is basis), which was below the 15% legal limit set by state feed regulations. Diets were formulated so that as the inclusion rate of AH increased, the amount of steam-flaked corn and soyhull pellets decreased and soybean meal inclusion increased. Experimental design was a replicated 4 × 4 Latin square. Diet had a cubic effect on actual milk yield, energy-corrected milk yield, and dry matter intake, with the 7% AH diet having the highest values and the 13% AH diet having the lowest. The percent and yield of total solids and the yields of lactose and fat did not differ with diet, but percent and yield of protein declined linearly with increased AH inclusion, and fat percent increased linearly. Apparent total-tract digestibilities of dry matter and organic matter were higher with the inclusion of AH in the diet. Total percentage of the day spent ruminating increased linearly with higher amounts of AH. Overall, this work demonstrated that AH can be fed at varying amounts, up to 20% of the diet, to lactating dairy cows to support high levels of milk production and that increasing amounts of AH (up to 20%) in the diet could lead to improved digestibility and milk fat percentage but decreased milk protein production.

Feed additives have received increasing attention as a viable means to reduce enteric emissions from ruminants, which contribute to total anthropogenic methane (CH4) emissions. The aim of this study was to investigate the efficacy of the commercial feed additive SOP STAR COW (SOP) to reduce enteric emissions from dairy cows and to assess potential impacts on milk production. Twenty cows were blocked by parity and days in milk and randomly assigned to one of two treatment groups (n = 10): supplemented with 8 g/day SOP STAR COW, and an unsupplemented control group. Enteric emissions were measured in individual head chambers over a 12-h period, every 14 days for six weeks. SOP-treated cows over time showed a reduction in CH4 of 20.4% from day 14 to day 42 (p = 0.014), while protein % of the milk was increased (+4.9% from day 0 to day 14 (p = 0.036) and +6.5% from day 0 to day 42 (p = 0.002)). However, kg of milk protein remained similar within the SOP-treated cows over the trial period. The control and SOP-treated cows showed similar results for kg of milk fat and kg of milk protein produced per day. No differences in enteric emissions or milk parameters were detected between the control and SOP-treated cows on respective test days.

Objective: This descriptive study with almond hulls (AH) aimed to determine if year and month influenced the probability of a violation occurring for percent crude fiber (as-is basis) and to assess the effect of moisture on violations. In California, the legal definition of AH is based on the percent crude fiber (as-is basis), percent moisture, and percent ash. Almond hulls cannot exceed 15% crude fiber, 13% moisture, and 9% ash. Materials and Methods: Data for a 5-yr period (2014 to 2018) were obtained from the California Department of Food and Agriculture through a CA Public Records Act request. There were 673 samples of AH that were analyzed for percent crude fiber and percent moisture. Results and Discussion: There were differences in the probability of violations for years and months. The highest percent crude fiber (as-is basis) occurred in 2014 and the lowest in 2016. Almond hull samples found to be in violation were 4.1 percentage units higher in crude fiber content, 17.4 versus 13.3% crude fiber as-is basis, than those not in violation across all 5 yr. Percent crude fiber (as-is basis) was greater in summer than other seasons. Implications and Applications: As the percent moisture in the AH increased, the risk of a violation decreased as the percentage of crude fiber on an as-is basis decreased. The proportion of AH samples found to contain greater than 15% crude fiber (as is) over the 5-yr period ranged from 39 to 62% with few samples in violation based on moisture.

Societal pressure to reduce enteric methane emissions from cattle continues to increase. The present study evaluated the efficacy of the commercial essential oil feed additive Agolin® Ruminant on reducing enteric gas emissions and improving milk parameters in dairy cattle. Twenty mid-lactation Holstein cows, blocked by parity and days in milk, were randomly assigned to a top dress treatment with Agolin or an un-supplemented control for a 56-day trial. Cows were group housed and individually fed twice daily. Enteric gas emissions, including methane, carbon dioxide, ammonia, and nitrous oxide, were sampled every 14 days for a 12 h period via head chambers connected to a mobile air quality laboratory. Cows supplemented with Agolin versus the control had less methane intensity (g/period/kg energy-corrected milk (ECM); p = 0.025). Ammonia was the most affected gas, with lower ammonia production (mg/period; p = 0.028), and ammonia intensity (mg/period/kg ECM; p = 0.011) in Agolin-fed versus control-fed cows. All cow performance variables, including dry matter intake, ECM, milk fat, milk protein, or feed efficiency were similar between treatments. Further research should evaluate how Agolin impacts ruminal flora, focusing on mechanistic impacts to fermentation.

Objective: Prophylactic supplementation of psyllium husk is recommended to enhance passage of ingested sand from the gastrointestinal tracts of horses. We hypothesized that psyllium supplementation would increase fecal sand passage and favorably alter bacterial populations in the hindgut. Six yearlings and six mature mares were fed a psyllium supplement in the diet daily for seven days. Voluntarily-voided feces were collected over the course of 29 days, prior, during, and after treatment. Feces were analyzed for acid detergent fiber (ADF) and acid detergent insoluble ash analyses. Microbial DNA was also isolated, and the V4 region of the 16S ribosomal RNA gene was PCR-amplified and sequenced using MiSeq technology.Results: Fecal ADF concentration was greater in adults while silica concentration was greater in yearlings. Mature mare fecal ADF decreased during and just after supplementation but thereafter increased. No changes in silica levels were noted in either group over time. Fecal microbial population phylogenetic diversity was greatest mid-supplementation and lowest at 11 days post-supplementation. Functional profiles of the microbial communities presented some benefits for psyllium supplementation. These findings provide compelling evidence for further detailed studies of prophylactic psyllium supplementation.

Objective: The aim of this research was to determine the nutritional composition of different varieties of almond hulls (AH) along with the total, pure, or non-hull material of almond hulls. Materials and Methods: Twelve samples of commercial almond hulls were used. Each sample was divided into 2 subsamples. One subsample represented the commercial almond hulls (total hulls). The other half was hand sorted to separate the hulls (pure hulls) from non-hull sticks and shells (debris). These samples were then ground for subsequent chemical analysis. Results and Discussion: Reducing the proportion of debris in AH reduced the fiber and ash content. The Nonpareil variety was superior in quality as measured by greater sugar content and lower content of ash, lignin, and NDF compared with other varieties. Crude fiber was more closely associated with aNDFom (ash-free aNDF) rather than aNDF (NDF assayed with heat-stable amylase), suggesting that any change in the fiber definition of AH should be based on fiber content that is ash free. Implications and Applications: The results from this study will help dairy nutritionists to better formulate diets including AH for lactating dairy cows. Almond huller operations can also use these findings to better understand how debris affects the composition of almond varieties to help stay below the legal concentration of crude fiber in AH being sold as feed. In addition, this information will aid the California Department of Food and Agriculture in making any changes to feed laws regulating the fiber composition of AH.

Antimicrobial resistance is a global public health concern, and livestock play a significant role in selecting for resistance and maintaining such reservoirs. Here we study the succession of dairy cattle resistome during early life using metagenomic sequencing, as well as the relationship between resistome, gut microbiota, and diet. In our dataset, the gut of dairy calves serves as a reservoir of 329 antimicrobial resistance genes (ARGs) presumably conferring resistance to 17 classes of antibiotics, and the abundance of ARGs declines gradually during nursing. ARGs appear to co-occur with antibacterial biocide or metal resistance genes. Colostrum is a potential source of ARGs observed in calves at day 2. The dynamic changes in the resistome are likely a result of gut microbiota assembly, which is closely associated with diet transition in dairy calves. Modifications in the resistome may be possible via early-life dietary interventions to reduce overall antimicrobial resistance.

Water is essential in livestock production systems. In typical dairy production systems, 90% of the total water used by a dairy farm is attributed to feed production. Theoretically, ration manipulation is a method to potentially reduce the irrigation water needed for feed crops without dramatically increasing diet costs. However, published quantitative studies on the relationship between feed production and water use that are integrated with linear programming models are scarce. The overall objective of this study was to develop an optimization framework that could achieve a balance between minimization of dietary costs and dietary irrigation water usage, and that could be used as a framework for future research and models for various livestock production systems. Weighted goal programming models were developed to minimize the dietary costs and irrigation water usage for a hypothetical cow under 8 different environmental scenarios. The environmental conditions used a 2 × 2 × 2 factorial design, including 2 atmospheric CO2 concentrations (400 and 550 ppm), 2 water years (dry and wet), and 2 irrigation methods (furrow and drip). A systematic weighting scheme was used to model the trade-off between minimizing diet cost and minimizing irrigation water use for feedstuffs. Each environmental condition generated a set of distinct diets, which each met the same nutrient requirements of the hypothetical cow but had a different water usage when the weighting scheme was changed from weighting minimum diet costs to minimum irrigation water usage. For water resource planning in areas of dairy production, this set of unique solutions provides the decision maker with different feeding options according to diet cost, water usage, and available feeds. As water was more constrained, dietary dry matter intake increased, concentrations of neutral detergent fiber, ether extract, and energy decreased, and the concentration of lignin increased because less nutritive but more water-saving feedstuffs were included in the diet. Mitigation costs of water usage were calculated from goal programming results and indicated that the potential value of water under water-limited conditions (e.g., in a drought region) was higher than that under water-sufficient conditions. However, a smaller increase in feed costs can initially significantly reduce water usage compared with that of a least-cost diet, which implies that the reduction of water usage through ration manipulation might be possible. This model serves as a framework for the study of irrigation water usage in dairy production and other livestock production systems and for decision-making processes involved in water resources planning in the broader area of animal production.

While the environmental impacts of livestock production, such as greenhouse gas emissions and water usage, have been studied for a variety of US livestock production systems, the environmental impact of US sheep production is still unknown. A cradle-to-farm gate life cycle assessment (LCA) was conducted according to international standards (ISO 14040/44), analyzing the impacts of CS representing five different meat sheep production systems in California, and focusing on carbon footprint (carbon dioxide equivalents, CO2e) and irrigated water usage (metric ton, MT). This study is the first to look specifically at the carbon footprint of the California sheep industry and consider both wool and meat production across the diverse sheep production systems within California. This study also explicitly examined the carbon footprint of hair sheep as compared with wooled sheep production. Data were derived from producer interviews and literature values, and California-specific emission factors were used wherever possible. Flock outputs studied included market lamb meat, breeding stock, 2-d-old lambs, cull adult meat, and wool. Four different methane prediction models were examined, including the current IPCC tier 1 and 2 equations, and an additional sensitivity analysis was conducted to examine the effect of a fixed vs. flexible coefficient of gain (kg) in mature ewes on carbon footprint per ewe. Mass, economic, and protein mass allocation were used to examine the impact of allocation method on carbon footprint and water usage, while sensitivity analyses were used to examine the impact of ewe replacement rate (% of ewe flock per year) and lamb crop (lambs born per ewe bred) on carbon footprint per kilogram market lamb. The carbon footprint of market lamb production ranged from 13.9 to 30.6 kg CO2e/kg market lamb production on a mass basis, 10.4 to 18.1 kg CO2e/kg market lamb on an economic basis, and 6.6 to 10.1 kg CO2e/kg market lamb on a protein mass basis. Enteric methane (CH4) production was the largest single source of emissions for all CS, averaging 72% of total emissions. Emissions from feed production averaged 22% in total, primarily from manure emissions credited to feed. Whole-ranch water usage ranged from 2.1 to 44.8 MT/kg market lamb, almost entirely from feed production. Overall results were in agreement with those from meat-focused sheep systems in the United Kingdom as well as beef raised under similar conditions in California.

BACKGROUND Lignin is a complex, phenolic polymer found in plant cell walls that is essential for mechanical support, water and mineral transport, and defense in vascular plants. Over ten different enzymes play a role in the synthesis of lignin in plants. Suppression of any one enzyme or combinations of these enzymes may change the concentration and composition of lignin in the genetically transformed plants. Two lines of alfalfa that were downregulated for caffeoyl coenzyme A O-methyltransferase were used to assess the impact of lignin downregulation on chemical composition and fermentation rate and extent using an in vitro gas production technique. A total of 64 samples consisting of two reduced lignin (RL) and two controls (CL), four field replicates, two cutting intervals (CIs; 28 and 35 days), and two cuts (Cut-1 and Cut-3) were used. RESULTS No differences were detected in yield, crude protein, neutral detergent fiber (aNDF), and acid detergent fiber between the lines when harvested at the 28-day CI. The acid detergent lignin (ADL) concentration in RL alfalfa lines was significantly (P < 0.001) lower than in the CL. In alfalfa harvested at the 35-day CI, the RL alfalfa resulted in lower (P < 0.001) yield than CL. RL alfalfa lines had 24% and 22% lower (P < 0.001) ADL in Cut-1 and Cut-3 respectively than CL lines. The in vitro dry matter digestibility and aNDF digestibility (both as determined by the near-infrared reflectance method) were greater (P < 0.001) in RL than in CL lines harvested at the 35-day CI. In alfalfa harvested at the 35-day CI, extent of in vitro gas production and metabolizable energy content were greater in RL than in CL alfalfa. RL lines had 3.8% indigestible aNDF per unit ADL, whereas CL had 3.4% (P < 0.01). The positive effect of lignin downregulation was more pronounced when intervals between harvests were longer (35-day CI compared with the 28-day CI). CONCLUSION Lignin downregulation in alfalfa offers an opportunity to extend harvesting time (CI) for higher yield without compromising the nutritional quality of the alfalfa forage for dairy and livestock feeding. However, the in vitro results reported here warrant further study using in vivo methods. © 2018 Society of Chemical Industry.

The objective of the study was to quantify the rate of urea hydrolysis in dairy cattle manure under different initial urea concentration, temperature, and pH conditions. In particular, by varying all 3 factors simultaneously, the interactions between them could also be determined. Fresh feces and artificial urine solutions were combined into a slurry to characterize the rate of urea hydrolysis under 2 temperatures (15°C and 35°C), 3 urea concentrations in urine solutions (500, 1,000, and 1,500 mg of urea-N/dL), and 3 pH levels (6, 7, and 8). Urea N concentration in slurry was analyzed at 0.0167, 1, 2, 4, 6, 8, 12, 16, 20, and 24 h after initial mixing. A nonlinear mixed effects model was used to determine the effects of urea concentration, pH, and temperature treatments on the exponential rate of urea hydrolysis and to predict the hydrolysis rate for each treatment combination. We detected a significant interaction between pH and initial urea level. Increasing urea concentration from 1,000 to 1,500 mg of urea-N/dL decreased the rate of urea hydrolysis across all pH levels. Across all pH and initial urea levels, the rate of urea hydrolysis increased with temperature, but the effect of pH was only observed for pH 6 versus pH 8 at the intermediate initial urea concentration. The fast rates of urea hydrolysis indicate that urea was almost completely hydrolyzed within a few hours of urine mixing with feces. The estimated urea hydrolysis rates from this study are likely maximum rates because of the thorough mixing before each sampling. Although considerable mixing of feces and urine occurs on the barn floor of commercial dairy operations from cattle walking through the manure, such mixing may be not as quick and thorough as in this study. Consequently, the urea hydrolysis rates from this study indicate the maximum loss of urea and should be accounted for in management aimed at mitigating ammonia emissions from dairy cattle manure under similar urea concentration, pH, and temperature conditions reported in this experiment.

ABSTRACT Effects of feeding lipid supplements high in free fatty acids (FAs) of palmitate (C16:0) or stearate (C18:0) plus C18:1 cis 9&10 on milk yield and composition, apparent whole-tract apparent digestibility of FA, and the FA composition of milk lipids were studied. Four lactating Holstein cows with ruminal cannulae were used in a 4 × 4 Latin square assignment of four dietary treatments. Lipid supplements were enriched in free fatty concentrations of either palmitic acid (P) or stearic acid (S). The total mixed-ration contained 20 g/kg of lipid supplement that consisted of varying proportions of P to S. Treatments were: 100:0 P:S (P), 0:100 P:S (S), and two mixtures including 66:34 P:S (PS) and 34:66 P:S (SP). Milk yield and dry matter intake were not affected by lipid supplement, but the concentration and yield of fat in milk increased with increasing C16:0 in the lipid supplement. Increasing the C16:0 concentration in the lipid supplement increased its concentration in milk lipids while increasing C18:0 in the lipid supplement increased C18:0 concentration in milk fat. Whole-tract apparent digestibility of neutral detergent fiber (NDF) did not differ with lipid supplement, but organic matter digestibility tended to decrease with increasing C18:0 in the lipid supplement. Whole-tract digestibility of total FAs decreased with the increasing proportion of C18:0 to C16:0 in the lipid supplement. Apparent digestibility of C16:0 and C18:0 was not different within dietary treatment. The FA composition of the lipid supplement impacted both whole-tract digestibility of FAs and FA composition of milk lipids.

Lignin is composed of cross-linked phenolic compounds that impact forage quality. As forage plants mature, lignin concentration increases and DM and fiber digestibility decrease. Low-lignin alfalfa varieties offer potential for improved forage quality and animal production as well as increased yield by allowing for harvests at later maturity while maintaining high digestibility. Lignin synthesis in alfalfa was reduced by genetic manipulation through suppressing enzymes in the lignin biosynthetic pathway. In the current study, two genetically modified alfalfa lines (LL) and their respective controls (CL) were used to study the effect of reduced lignin content on in vitro gas production and predicted ME concentration. Sixty-four samples, that is, four alfalfa lines (two LL and two CL), four field replicates, two cuttings (cut 1 and 3), and two cutting schedules (28 and 35 d), were used. An in vitro technique was used to determine differences in in vitro gas production and predicted ME concentration between two CL and two LL varieties of alfalfa. Alfalfa samples were compared at cuttings 1 and 3 as well as cutting schedules that occurred at 28 and 35 d. Ground alfalfa samples were incubated in buffered rumen fluid using an in vitro gas technique at various time points over 72 h to determine the influence of lignin on rate and extent of in vitro gas production. Four in vitro incubations were conducted, and rate and extent of gas production were calculated using an exponential model. The ME was estimated using the 24 h gas production and CP content of each sample as described by Menke and Steingass (1988). Total ME (P < 0.0001) and rate of gas production (P < 0.0001) were higher in the LL varieties than the CL varieties, whereas no significant difference was found in extent of gas production. Low-lignin alfalfa varieties offer potential to increase the ME concentration in alfalfa, which needs to be further evaluated by animal feeding studies.

Cow's milk has a low concentration of β-carotene (BC) due in part to low BC concentrations in feedstuffs, limited absorption of BC in the small intestine, and metabolism by and storage in tissues. There is also a phenomenon not well understood where dietary BC appears to be degraded in the rumen. Previously, a whey protein-based composite gel was demonstrated to increase the omega-3 concentrations in cow's milk by protecting the unsaturated fatty acids from biohydrogenation in the rumen. Our hypothesis was that the same technology if applied to BC would increase the BC concentration in the milk of Jersey cows. Jersey cows were used because this breed tends to have a higher concentration of BC in their milk than Holstein cows. The objective was to test the efficacy of a whey protein-based composite gel to protect BC from rumen degradation and increase the BC concentration of Jersey milk. Four primiparous and four multiparous Jersey cows were fed a basal total mixed-ration with 500 mg BC fed in 2 physical forms, either in a whey protein-based composite gel (GEL) or as free, rumen available BC (CTL) in a crossover design. The BC was fed once daily at the morning feeding. Periods were 21 d with a 2-wk interval between periods to minimize carryover effects. Concentrations of BC were measured in blood plasma and milk. Feeding the GEL significantly increased BC concentration in plasma by 0.6619 μg/ml in primiparous cows 0.6620 μg/ml in multiparous cows (P < 0.0001), but no significant increase in BC concentration occurred in milk. The WPI gel was effective in increasing the BC concentration of plasma; however, further research should address the transfer of BC from blood into milk.

The aim was to determine the effect of feeding either a low (121.2 g/kg of DM) or a high (793.1 g/kg of DM) palmitic acid supplemental fat to lactating Holstein cows on milk yield and composition and changes in thermal properties of the milk fat. There are numerous studies reporting the effect of dietary lipids high in palmitic acid on animal performance, but few reports determined the effect on the thermal properties of the milk fat produced. Cows fed the high palmitic diet showed increased (P < 0.001) fat content and produced more 4% FCM. Concentration of palmitic acid in milk was greater (P < 0.001) for the high palmitic than low palmitic diet. Textural analysis of butter showed that anhydrous milk fat from high palmitic cows was harder (P < 0.001) at both ambient and 10°C temperatures compared with that from low palmitic cows. Temperatures at onset of melting and peak of melting of butter from high palmitic cows were greater than low palmitic cows. Feeding a high palmitic acid supplement to lactating cows changed the fatty acid composition of milk lipids and modified their functional property, which was illustrated by a harder butter. The implications are that feeding lipid supplements high in palmitic acid could affect the physicochemical properties of dairy products, butter in particular, but also potentially other dairy products that contain milk fat.