Does silage containing plantain affect the urination behaviour and urinary nitrogen of dry cows grazing diverse or conventional pasture?

The objective of this study was to investigate the effect of diverse silage containing plantain on urination behaviour and urinary and faecal nitrogen (N) concentration of dairy cows when grazing standard ryegrass-white clover (RGWC) or diverse pasture containing plantain. Four groups of six non-lactating dairy cows were balanced and randomly assigned to one of four dietary treatments in a 2 × 2 factorial design: RGWC pasture plus RGWC silage; RGWC pasture plus diverse silage containing plantain; diverse pasture plus RGWC silage; diverse pasture plus diverse silage. Urination behaviour (frequency and volume) was continuously measured for a minimum of 24 hours on four cows per treatment using the Lincoln University PEETER V1.0 sensor. There was no silage or silage × pasture type interaction effects on urination behaviour, though diverse pasture regardless of silage increased daily urination frequency (p=0.046) and daily urine volume (p=0.003) of cows by 27% and 31% respectively, compared to RGWC. Spot urine N% concentration was similar among treatments, but faecal N% tended (p=0.07) to be higher in cows grazing diverse pasture compared to those grazing RGWC with no silage type effect. Unlike fresh plantain, silage containing plantain does not seem to alter urination behaviour or N excretion of dairy cattle

Effect of farm system and milk urea phenotype on milk yield and milk composition of dairy cows in Canterbury

To investigate the effect of farm system, and cow selection for milk urea nitrogen (MUN), on milk yield and milk composition, a farmlet study was carried out between October 2018 and May 2019 in Lincoln, Canterbury. A farm system with a low stocking rate and low N fertiliser input (LSR, 2.9 cows/ha) sown with a conventional ryegrass clover and plantain diverse pastures was compared with a farm system with a moderate stocking rate and moderate N fertiliser (MSR, 3.9 cows/ha) using conventional ryegrass and white clover pastures and supplementing 3 kg DM/cow/d as crushed barley grain. Each farmlet had total herd size of 40 mixed-age HF x J spring-calving dairy cows which included six cows selected solely for a high MUN or a low MUN. There was no effect of farm system on milk fat, protein or lactose content but MUN was lower in LSR compared with MSR. Milk production was also lower for LSR (466 vs 429±12.4 kg MS/cow/ha, P<0.05), owing to poorer quality diet in mid lactation. Cows selected for low MUN tended to produce less milk compared with high MUN cows (4478 vs 3987±174 kg/cow, P<0.10) though this was partially offset by increased protein content in milk of low MUN cows. Farm system and animal selection for MUN have a greater impact on milk yield than on milk composition

Relationship between social dominance and milk production of dairy cows grazing pasture

The objectives of this experiment were to study factors determining social dominance of grazing dairy cows and the relationship between social dominance and milk production under grazing systems. A total of 252 spring calving Friesian x Jersey dairy cows in three groups differing in stocking rate and herd size grazing perennial ryegrass and white clover pasture were observed for three months in early lactation to determine their dominance value. All cows ranged in age from 2 to 11 years and live weight (LW) ranged from 340 kg to 648 kg. Dominance values were determined by social interactions indicating dominance and submission between cows. Social interactions were recorded on a win and loss basis. In all three groups, the dominance value was positively correlated (P<0.05) with age (r = 0.42 to 0.65), live weight (r = 0.33 to 0.47) and milk production (r = 0.32 to 0.42), but no relationship with body condition score was found. In conclusion, older cows with higher live weight were more dominant and tended to have higher milk productio

Review: Markers and proxies to monitor ruminal function and feed efficiency in young ruminants

Developing the rumen’s capacity to utilise recalcitrant and low-value feed resources is important for ruminant production systems. Early-life nutrition and management practices have been shown to influence development of the rumen in young animals with long-term consequences on their performance. Therefore, there has been increasing interest to understand ruminal development and function in young ruminants to improve feed efficiency, health, welfare, and performance of both young and adult ruminants. However, due to the small size, rapid morphological changes and low initial microbial populations of the rumen, it is difficult to study ruminal function in young ruminants without major invasive approaches or slaughter studies. In this review, we discuss the usefulness of a range of proxies and markers to monitor ruminal function and nitrogen use efficiency (a major part of feed efficiency) in young ruminants. Breath sulphide and methane emissions showed the greatest potential as simple markers of a developing microbiota in young ruminants. However, there is only limited evidence for robust indicators of feed efficiency at this stage. The use of nitrogen isotopic discrimination based on plasma samples appeared to be the most promising proxy for feed efficiency in young ruminants. More research is needed to explore and refine potential proxies and markers to indicate ruminal function and feed efficiency in young ruminants, particularly for neonatal ruminants

Urine and fecal excretion patterns of dairy cows divergent for milk urea nitrogen breeding values consuming either a plantain or ryegrass diet

Environmental degradation has been attributed to inefficient nitrogen utilization from pastoral dairy production systems. This degradation has especially been associated with the urine patch, which has been identified as a key component of nitrate leaching to waterways. However, a lack of information exists regarding the pattern of urination events and individual urination characteristics across the day, which would help inform strategic management decisions. The aim of this study was therefore to evaluate and report the patterns and characteristics of fecal and urination events throughout the day for cows divergent for milk urea nitrogen breeding values (MUNBV) on either a plantain [Plantago lanceolata L. (PL)] or ryegrass [Lolium perenne L. (RG)] diet as ways to reduce environmental impact. Sixteen multiparous lactating Holstein Friesian × Jersey cows divergent for MUNBV were housed in metabolism crates for 72 h, with all excretion events captured and analyzed. Cows selected as low for MUNBV consistently had a 65.2-kg lower urinary urea nitrogen (UUN) load (kg/ha) than high MUNBV cows for all hours of the day when consuming RG. The association between lower urinary urea loading rates and less N leaching implies a reduced environmental impact from low MUNBV cows consuming RG. When cows consumed PL, regardless of MUNBV, they had on average a 137.5-kg (UUN/ha) lower loading rate compared with high MUNBV cows on RG and a 72.2-kg (UUN/ha) lower loading rate compared with low MUNBV cows consuming RG across the day. Cows on PL also exhibited a different diel pattern of UUN load compared with cows consuming RG. Differences in the diel pattern of N excreted in feces were also detected based on MUNBV and by diet, with low MUNBV cows excreting on average 3.06 g more N in feces per event for the majority of the day compared with high MUNBV cows when consuming RG. Lower UUN loading rates and more N excreted in feces indicate a potentially lower environmental impact from low MUNBV cows when consuming RG compared with high MUNBV cows. The use of the PL diet also resulted in lower UUN loading rates and greater levels of N excreted in feces compared with RG, therefore also indicating its ability to reduce environmental impact compared with RG

Nitrogen balance of dairy cows divergent for milk urea nitrogen breeding values consuming either plantain or perennial ryegrass

Inefficient nitrogen (N) use from pastoral dairy production systems has resulted in environmental degradation, as a result of excessive concentrations of urinary N excretion leaching into waterways and N₂O emissions from urination events into the atmosphere. The objectives of this study were to measure and evaluate the total N balance of lactating dairy cows selected for milk urea N concentration breeding values (MUNBVs) consuming either a 100% perennial ryegrass (Lolium perenne L.) or 100% plantain (Plantago lanceolata L.) diet. Sixteen multiparous lactating HolsteinFriesian × Jersey cows divergent for MUNBV were housed in metabolism crates for 72 h, where intake and excretions were collected and measured. No effect of MUNBV was detected for total N excretion; however, different excretion characteristics were detected, per urination event. Low MUNBV cows had a 28% reduction in the concentration of urinary urea nitrogen (g/event) compared to high MUNBV cows when consuming a ryegrass diet. Cows consuming plantain regardless of their MUNBV value had a 62% and 48% reduction in urinary urea nitrogen (g/event) compared to high and low MUNBV cows consuming ryegrass, respectively. Cows consuming plantain also partitioned more N into faeces. These results suggest that breeding for low MUNBV cows on ryegrass diets and the use of a plantain diet will reduce urinary urea nitrogen loading rates and therefore estimated nitrate leaching values, thus reducing the environmental impact of pastoral dairy production systems

Estimation of nitrogen use efficiency for ryegrass-fed dairy cows: model development using diet and animal-based proxy measures

This study aimed to identify suitable predictors of nitrogen (N) use efficiency (NUE; milk N/N intake) for cows that differed in breeds and were fed with ryegrass pasture, using existing data from the scientific literature. Data from 16 studies were used to develop models based on the relationships between NUE and dietary and animal-based factors. Data from a further 10 studies were used for model validation. Milk urea N (MUN) and dietary water-soluble carbohydrate-to-crudeprotein ratio (WSC/CP) were the best and most practical animal- and diet-based proxies to predict NUE. The results indicate that it might be necessary to adopt separate models for different breeds when using WSC/CP to predict NUE but not when using MUN

Can low input dairy systems be economically and environmentally sustainable? Results from a farmlet study

A two-year dairy study was conducted under irrigation at Lincoln, Canterbury, comparing 1. Moderate stocking rate (MSR, 3.9 cows/ha; comparative stocking rate (CSR) of 89 kg live weight (LWT)/t DM (dry matter) offered; 150 kg nitrogen (N) fertiliser/ha/year; grain supplementation of 0.55 t DM/cow/year; wintering cows off- farm); or 2. Low stocking rate (LSR, 2.9 cows/ha; CSR of 91 kg LWT/t DM offered; grazing diverse pasture (Italian ryegrass, plantain, red- and white clover); 103 kg N fertiliser/ha/year; wintering cows on-farm). The Lincoln University Dairy Farm (LUDF; 3.4 cows/ha; CSR of 76 kg LWT/t DM offered; 169 kg N fertiliser/ha/year) was the benchmark. Milk yield, pasture production and quality data were modelled in FARMAX and OverseerFM to estimate financial and environmental performance of each farm. Performance was similar for MSR and LUDF. LSR gave the best environmental outcome across 2018/19 and 2019/20, leaching approximately 31% less N compared with MSR and LUDF. However, annual milk solids per ha were 28% less for LSR relative to MSR and LUDF. Correspondingly, the annual operating profit per ha was 35% less for LSR compared with LUDF. These financial losses can be mitigated in an LSR system if the farmer adopts more complex pasture management

Dairy cows with different milk urea nitrogen breeding values display different grazing behaviours

The objective of this study was to describe the diurnal pattern of grazing behaviour of multi-parous dairy cows divergent for milk urea N breeding values (MUNBV) and the consistency of these differences across different sward compositions (perennial ryegrass [RG; Lolium perenne L.] or ryegrass with plantain [Plantago lanceolata L.; RGPL]) and stages of lactation (early and late lactation). Jaw movement recorders were fitted to 24 animals in early lactation and 16 cows in late lactation, in early lactation 12 cows were assigned to the ryegrass diet and 12 cows assigned to the plantain diet, in late lactation 8 cows were assigned to ryegrass with the remaining 8 cows assigned to the plantain diet. For each diet half of the animals during both stages of lactation were classified as high for MUNBV and the other half as low for MUNBV. Low MUNBV animals had more mastications per bite over the day (P < 0.01) with a one-unit decrease in MUNBV resulting in 0.07 more bites per mastication during the first two grazing bouts, as well as differences in the temporal distribution of grazing bouts compared with high MUNBV cows. A one-unit decrease in MUNBV resulted in a 0.11 ± 0.02 increase in mastications per bite during the first grazing bout across both stages of lactation and sward composition. Ingestive behaviour has a large impact on the physical features of ingesta and thereby rumen function. The results of this study indicate that dairy cows divergent for MUNBV grazing the same forage apply different grazing strategies in terms of oral processing of ingesta and diurnal meal pattern. These results present potential explanatory variables for phenotypical differences observed in dairy cows divergent for MUNBV

Estimation of nitrogen use efficiency for ryegrass-fed dairy cows: Model development using diet- and animal-based proxy measures

This study aimed to identify suitable predictors of nitrogen (N) use efficiency (NUE; milk N/N intake) for cows that differed in breeds and were fed with ryegrass pasture, using existing data from the scientific literature. Data from 16 studies were used to develop models based on the relationships between NUE and dietary and animal-based factors. Data from a further 10 studies were used for model validation. Milk urea N (MUN) and dietary water-soluble carbohydrate-to-crudeprotein ratio (WSC/CP) were the best and most practical animal- and diet-based proxies to predict NUE. The results indicate that it might be necessary to adopt separate models for different breeds when using WSC/CP to predict NUE but not when using MUN