Evaluation and quantification of associations between commonly suggested milk biomarkers and the proportion of grassland-based feeds in the diets of dairy cows

This study is a first step approach towards the prediction of the proportion of grassland-based feeds (%GB) in dairy cow diets with the aid of three different groups of milk biomarkers. We aimed to evaluate and quantify the associations between biomarkers commonly suggested in the literature and %GB in individual cows as a hypothesis-generating stage for the prospective establishment of accurate %GB prediction models. Consumers and governments financially encourage sustainable, local milk production making grass-based feeding, in grassland-dominated regions, of major interest. Milk from grassland-fed cows differs from that of other feeding systems by inferential fatty acids (FA), β-carotene content and yellow color; however, these biomarkers have not been evaluated together for their association with %GB. Using approved methods of parametric regression analysis, gas chromatography (GC), mid-infrared spectra (MIR) and color spectroscopy, we aimed to develop a first step towards an easy-to-implement, cost-effective milk-based control to estimate %GB in dairy cow diets. The underlying database was generated with 24 cows each fed one of 24 different diets gradually increasing in grass silage and decreasing in corn silage. Our results indicate that GC-measured α-linolenic acid, total n-3 FA and the n-6:n-3 ratio, MIR-estimated PUFA and milk red-green color index a* are robust milk biomarkers for constructing accurate prediction models to determine %GB. Based on simplified regression analysis, diets containing 75% GB should contain ≥ 0.669 and 0.852 g α-linolenic acid and total n-3 FA per 100 g total FA, respectively, and an n-6:n-3 FA ratio of < 2.02 measured with GC; estimated with MIR, polyunsaturated FA should be ≥ 3.13 g/100 g total FA. β-carotene was not a good predictor for estimating %GB. Unexpectedly, the milk became greener with increasing %GB (negative a* values, ‒6.416 for 75% GB), suggesting the red-green color index, not yellow-blue, as a suitable biomarker

The Role of the Medial Prefrontal Cortex in Regulating Social Familiarity-Induced Anxiolysis

Overcoming specific fears and subsequent anxiety can be greatly enhanced by the presence of familiar social partners, but the neural circuitry that controls this phenomenon remains unclear. To overcome this, the social interaction (SI) habituation test was developed in this lab to systematically investigate the effects of social familiarity on anxiety-like behavior in rats. Here, we show that social familiarity selectively reduced anxiety-like behaviors induced by an ethological anxiogenic stimulus. The anxiolytic effect of social familiarity could be elicited over multiple training sessions and was specific to both the presence of the anxiogenic stimulus and the familiar social partner. In addition, socially familiar conspecifics served as a safety signal, as anxiety-like responses returned in the absence of the familiar partner. The expression of the social familiarity-induced anxiolysis (SFiA) appears dependent on the prefrontal cortex (PFC), an area associated with cortical regulation of fear and anxiety behaviors. Inhibition of the PFC, with bilateral injections of the GABAA agonist muscimol, selectively blocked the expression of SFiA while having no effect on SI with a novel partner. Finally, the effect of D-cycloserine, a cognitive enhancer that clinically enhances behavioral treatments for anxiety, was investigated with SFiA. D-cycloserine, when paired with familiarity training sessions, selectively enhanced the rate at which SFiA was acquired. Collectively, these outcomes suggest that the PFC has a pivotal role in SFiA, a complex behavior involving the integration of social cues of familiarity with contextual and emotional information to regulate anxiety-like behavior

Rapid responses in bovine milk fatty acid composition and phenol content to various tanniferous forages

acceptedVersionpublishedVersio

Rapid responses in bovine milk fatty acid composition and phenol content to various tanniferous forages

Milk and dairy products considerably contribute to the nutritional value of human diets. In order to benefit human nutrition bovine milk fatty acid composition and phenol content are effectively manipulated by the cow’s diet. However, response times taken for these alterations to occur have not been quantified. In the present study, fatty acid composition and phenol content of the milk were evaluated after three days of feeding six cows six different diets, supplemented with six different tanniferous plants (hazel, silver birch, blackcurrant, grape vine, wood avens and rosebay willow with total tannin concentrations of 26, 36, 42, 52, 55 and 79 g/kg dry matter, respectively). Lucerne was applied as the low-phenol control diet. Substantial changes in total phenols and fatty acids were found in milk samples after just three days. Proportions of cis-9 trans-11 C18:2 and trans-11 C18:1 declined by 29 and 68%, respectively, in comparison to milk from cows fed lucerne, indicating a definitive ruminal biohydrogenation response. However, there were no significant effects between test plants and lucerne when comparing C18:3 n-3 and C18:2 n-6 proportions in milk fat. So, it was demonstrated that phenols and certain individual fatty acids in bovine milk can be rapidly modified by adding specific tanniferous plants to the diet.ISSN:1230-138

Effects of incremental increases in grass silage proportions from different harvest years on methane emissions, urinary nitrogen losses, and protein and energy utilisation in dairy cows

Dairy cows, methane and global warming have become publicly related terms. However, appropriate dairy cow management may in fact be part of the climate solution when viewed as part of the biogenic carbon cycle. Accordingly, governments and consumers are encouraging more sustainable, locally produced, climate friendly dairy production that often includes grassland-based feeding. However, this system is presumed to result in greater methane emissions compared to corn silage- or concentrate-based diets. An increase in urine nitrogen, associated with increased ammonia and nitrous oxide emission potential, questions the environmental usefulness of this strategy pertaining to global warming. This study is the first to compare the effects of incremental increases of grass silage proportion on enteric methane production as well as N and energy losses in dairy cows. Twenty-four mid- to end-lactation dairy cows were each fed one of 24 different diets, from two different harvest years, gradually increasing in grassland-based feeds (grass silage and hay) from about 500 to 1000 g/kg and concomitantly decreasing in corn silage. Each cow underwent a 7-day total collection period and was housed for 48 h in respiration chambers. Incremental data were subjected to an approved parametric regression analysis approach. The dietary increase in grassland-based feeds did not impair milk yield, N and energy utilisation. Simplified regression equations revealed that, contrary to current assumptions, there was a decline in methane production from 373 to 303 g/day when increasing grassland-based feeds from 500 to 1000 g/kg diet, and there was a trend for a decline in emission intensity from 20.6 to 17.6 g/kg of energy-corrected milk. However, urine nitrogen emissions clearly increased even when related to nitrogen intake; the latter from 260 to 364 g/kg when increasing grassland-based feeds from 500 to 1000 g/kg. Methane and urine nitrogen emissions were not affected by year of harvest.ISSN:0931-2439ISSN:1439-039

Effects of early herbage cutting and vine leaves on methane emission, urine nitrogen losses, and the milk fatty acid profile of dairy cows

Methane mitigation in dairy cows is an essential part of combating global warming. Governments and consumers have become increasingly interested in herbage-based feeding, and premium prices are often paid for these types of dairy products. However, this feeding strategy is presumed to produce more methane per unit of feed or milk than corn silage- or concentrate-based diets due to higher fiber intakes. Immature herbage is preferred to maintain dairy cow performance, but the high content of N and digestible fiber may increase methane and urine N emissions compared with more mature herbage. Tannin-containing feeds, such as vine leaves (Vitis vinifera), may help to combat the emissions associated with feeding immature herbage. Our study aimed to evaluate differences between early-stage (ES; 21 d of regrowth) versus late-stage (LS; 42 d) herbage and the effects of vine leaves on methane and nitrogenous emissions and the milk fatty acid profile of dairy cows. Twenty-four mid- to late-lactating dairy cows were randomized to 4 dietary groups (n = 6) in a factorial study design. Each of the 4 diets contained 69% fresh mixed legume-grass herbage, 13% grass hay, and 5% concentrate on a dry matter (DM) basis. Two diets were based on immature fresh mixed legume-grass herbage and grass hay (ES), and 2 contained more mature fresh mixed legume-grass herbage and grass hay (LS). Of these, 1 contained 13% vine leaves (VL+) and the other an additional 13% hay (VL−). No significant differences were observed in DM intake or milk yield across the diets. Methane emission intensity was lowest with ES-VL+ diets compared with LS-VL− diets (−30%; 17.1 vs. 24.5 mg/kg of energy-corrected milk). Methane yield decreased by 17% and 20% when related to the intake of DM and digested organic matter for ES-VL+ compared with LS-VL− diets (16.9 vs. 20.3 g/kg of DM intake; 23.5 vs. 29.3 g/kg of digestible organic matter). Immature grass and vine leaf addition each caused about half of the respective declines. Cows consuming any of the ES diets and the LS-VL+ diet consumed and excreted (urinary N) significantly more N than those consuming LS diets. However, when related to N intake, no differences were recorded. Unexpectedly, vine leaves did not mitigate urine N excretion; however, they lowered the n-6:n-3 ratio and increased concentrations of vaccenic and rumenic acids in both ES and LS diets. Our results demonstrate that feeding immature herbage in combination with vine leaves reduces methane yield; however, the associated high urinary N losses need to be addressed.ISSN:0022-0302ISSN:1525-319

Rapid responses in bovine milk fatty acid composition and phenol content to various tanniferous forages

acceptedVersionpublishedVersio

Evaluation and quantification of associations between commonly suggested milk biomarkers and the proportion of grassland-based feeds in the diets of dairy cows

This study is a first step approach towards the prediction of the proportion of grassland-based feeds (%GB) in dairy cow diets with the aid of three different groups of milk biomarkers. We aimed to evaluate and quantify the associations between biomarkers commonly suggested in the literature and %GB in individual cows as a hypothesis-generating stage for the prospective establishment of accurate %GB prediction models. Consumers and governments financially encourage sustainable, local milk production making grass-based feeding, in grassland-dominated regions, of major interest. Milk from grassland-fed cows differs from that of other feeding systems by inferential fatty acids (FA), β-carotene content and yellow color; however, these biomarkers have not been evaluated together for their association with %GB. Using approved methods of parametric regression analysis, gas chromatography (GC), mid-infrared spectra (MIR) and color spectroscopy, we aimed to develop a first step towards an easy-to-implement, cost-effective milk-based control to estimate %GB in dairy cow diets. The underlying database was generated with 24 cows each fed one of 24 different diets gradually increasing in grass silage and decreasing in corn silage. Our results indicate that GC-measured α-linolenic acid, total n-3 FA and the n-6:n-3 ratio, MIR-estimated PUFA and milk red-green color index a* are robust milk biomarkers for constructing accurate prediction models to determine %GB. Based on simplified regression analysis, diets containing 75% GB should contain ≥ 0.669 and 0.852 g α-linolenic acid and total n-3 FA per 100 g total FA, respectively, and an n-6:n-3 FA ratio of < 2.02 measured with GC; estimated with MIR, polyunsaturated FA should be ≥ 3.13 g/100 g total FA. β-carotene was not a good predictor for estimating %GB. Unexpectedly, the milk became greener with increasing %GB (negative a* values, ‒6.416 for 75% GB), suggesting the red-green color index, not yellow-blue, as a suitable biomarker.ISSN:1932-620