Neil R. Cox

The amount of shade influences the behavior and physiology of dairy cattle

The objective was to understand how the amount of shade (shade cloth blocking 99% of solar radiation) influenced the behavior and physiology of Holstein-Friesian dairy cattle managed on pasture. We compared behavior, body temperature, and respiration rate of cattle provided with 1 of 3 treatments for 5 d: access to 2.4m(2) or 9.6m(2) shade/cow, or no shade (n=4 groups/treatment, 10 animals/group). Behavioral observations were carried out between 1000 and 1550h. Cows spent more than twice as much time in the larger shade (24 vs. 50% of observations for 2.4m(2) and 9.6m(2) shade/cow, respectively, SED: 1.7%) and engaged in fewer aggressive interactions when more shade was provided (10.7 vs. 3.2 aggressive interactions/m(2) during 5.8h of observation for 2.4m(2) and 9.6m(2) shade/cow, respectively, SED: 3.16 interactions/m(2)). Time around the water trough increased when little or no shade was provided (11, 5, and 2% of observations within 4.5m of water trough for no shade, 2.4m(2), and 9.6m(2) shade/cow, SED: 2.4%). Respiration rate was higher when cows had less shade available (62, 57, and 51 breaths/min for no shade, 2.4m(2), and 9.6m(2) shade/cow, respectively, SED: 2.1 breaths/min). All cows used the shade more when 9.6m(2) shade/cow was provided; simultaneous use was observed in 15 versus 0% of observations in the 9.6m(2) and 2.4m(2) treatments on the warmest day, respectively. Weather conditions influenced both the behavioral and physiological responses, and these changes were more pronounced when less or no shade was available. Cows spent more time in shade and less time lying with increasing heat load. In addition, aggressive interactions in the shade, time around the water trough, mean body temperature, and respiration rate increased with environmental heat load. Our findings highlight the importance of determining and providing an effective amount of shade to cattle.

Dairy cattle prefer shade over sprinklers: Effects on behavior and physiology

Cattle will readily use shade in warm weather, but less is known about voluntary use of sprinklers. We examined preferences of 96 Holstein-Friesian dairy cows (milk yield: 12.7±3.48 kg per day; mean±SD) for sprinklers, shade, or ambient conditions after walking 2.0 km or 0.3 km before afternoon milking (n=48 cows/distance). Each cow was individually tested on 3 consecutive days with a different paired choice each day: 1) shade or sprinklers, 2) shade or ambient conditions, 3) sprinklers or ambient conditions. Average air temperature during testing was 22.3°C. Cows preferred shade over sprinklers (62 vs. 38% ± 5.0%; mean ± SE) and shade over ambient conditions (65 vs. 35% ± 5.1%; mean±SE). Cows showed no preference between sprinklers and ambient conditions (44% of the cows chose sprinklers, SE=5.3%). The preference for shade over sprinklers and ambient conditions increased with air temperature, solar radiation, and wind speed. Walking distance did not influence the preference for any treatment. Respiration rate was decreased most by sprinklers (38% decrease) but also decreased in shade and ambient conditions (17 and 13% decrease, respectively; standard error of the difference=4.7%). Similarly, surface temperature was decreased most by sprinklers (11.4% decrease), compared with that by shade (1.0% decrease), or that by ambient conditions (1.4% increase; standard error of the difference=1.82%). Furthermore, sprinklers reduced insect avoidance behaviors, including number of tail flicks and hoof stamps. In conclusion, dairy cattle preferred to use shade in summer despite sprinklers being more efficient in decreasing heat load and insect avoidance behavior.

Growth patterns of bacterial communities in the rhizoplane and rhizosphere of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) in long-term pasture

Rhizoplane bacteria in white clover roots (0–5 cm), perennial ryegrass roots (0–5 and 5–10 cm) and surrounding rhizosphere soil from a long-term pasture were studied for the rate of colony development over a 10 day period. Serial dilutions were inoculated onto 0.1 strength tryptose soy agar (TSA) and 0.1 strength modified Kings medium B (KB). Bacterial counts were made eight times over 10 days. Bacterial colony development (CD) and eco-physiological (EP) indices were calculated from these data. There were no significant differences in CD and EP indices of fluorescent pseudomonads growing on KB medium. After 5 days, the number of colonies developing on KB as a proportion of total colonies appearing over 10 days was lower for ryegrass roots than for soil (P < 0.05). The community structure derived from the colonies growing on 0.1 strength TSA showed that the rhizoplanes of white clover and ryegrass had a greater proportion of K-strategists and a smaller proportion of r-strategists than did the rhizosphere soil (P < 0.001). CD values for roots were significantly lower than those for soil (P < 0.001), while EP values were not significantly different. Randomly selected bacterial isolates were identified using the Microlog™ system. The fastest growing (24 h) strains belonged to the genera Pseudomonas and Bacillus spp. Other genera identified included Acinetobacter, Sphingomonas, Streptococcus, Cellulomonas, Comamonas, Xanthomonas and Erwinia. The slowest growing bacteria belonged to the genera Cellulomonas, Rhizobium, Xanthomonas and Erwinia.

Effects of chitin amendment of soil on microorganisms, nematodes, and growth of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.)

Effects of soil amendment with crabshell chitin on the growth of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.), and on populations of soil bacteria, fungi, and plant-parasitic and free-living nematodes were investigated in a pot trial. Five soil samples were collected from Te Puke (Paengaroa Shallow Sand, a Typic Hapludand) and five from Hamilton (Bruntwood silt loam, an Aquic Hapludand), New Zealand. Subsamples of each soil were either amended with chitin or unamended and planted with white clover and ryegrass. The ryegrass shoot weight in amended soil was greater (P<0.01), most probably due to N mineralised from chitin. A significantly lower (P<0.01) root: shoot ratio of ryegrass in the amended soil also suggested improved N availability, and therefore less root mass was needed to support a given shoot mass. A reduction in nodulation was observed in 12-day-old white clover seedlings (P<0.05) and also in 6-week-old seedlings (P<0.01). The shoot weight of white clover was significantly lower (P<0.05) in amended soil, possibly due to phytotoxic effects of chitin. Chitin increased (P<0.01) the populations of bacteria and fungi by 13-fold and 2.5-fold, respectively. The cyst nematode of white clover, Heterodera trifolii, was significantly reduced in chitin-amended soil, possibly due to increased levels of chitinase produced by rhizosphere microorganisms. Two other plant-parasitic nematodes, Pratylenchus spp. and Tylenchus spp., were also reduced in ryegrass roots and in soil as a result of the chitin amendment. However, the total number of free-living nematodes increased 5.4-fold in amended soil.

Statistical analysis of nitrous oxide emission factors from pastoral agriculture field trials conducted in New Zealand

Between 11 May 2000 and 31 January 2013, 185 field trials were conducted across New Zealand to measure the direct nitrous oxide (N2O) emission factors (EF) from nitrogen (N) sources applied to pastoral soils. The log(EF) data were analysed statistically using a restricted maximum likelihood (REML) method. To estimate mean EF values for each N source, best linear unbiased predictors (BLUPs) were calculated. For lowland soils, mean EFs for dairy cattle urine and dung, sheep urine and dung and urea fertiliser were 1.16 ± 0.19% and 0.23 ± 0.05%, 0.55 ± 0.19% and 0.08 ± 0.02% and 0.48 ± 0.13%, respectively, each significantly different from one another (p < 0.05), except for sheep urine and urea fertiliser. For soils in terrain with slopes >12°, mean EFs were significantly lower. Thus, urine and dung EFs should be disaggregated for sheep and cattle as well as accounting for terrain.

Changes in composition and quality characteristics of ovine meat and fat from castrates and rams aged to 2 years

Abstract A comprehensive set of quality parameters has been recorded for meat and fat from groups of castrate and ram lambs raised on pasture and slaughtered in groups of six at 91‐day intervals from 122 to 668 days of age. These include mechanical evaluation of meat tenderness, sensory evaluations of meat flavour and fat odour, and measurements of fat colour, fatty acid composition, vitamins C and E, free glucose and iron in the meat, and of the concentrations of the flavour compounds indoles, phenols, and branched chain fatty acids in the fat. There was significant variation in many parameters between slaughter days, including markedly lower meat tenderness in one slaughter group, probably in response to unfavourable pasture conditions. Older ram lambs tended to be less tender than castrates of the same age. However, no longer‐term age‐related trends were observed in tenderness or flavour quality. Concentrations of free glucose in rigor muscle and vitamin C showed a declining trend with age. Concentrations of the branched chain fatty acids 4‐methyloctanoic and 4‐methylnonanoic acids in fat increased with age. Sex category effects were observed for the branched chain fatty acids and for indole and skatole. Higher concentrations were observed in ram lambs. The data indicate there is only a limited decline in lamb meat quality characteristics up to nearly 2 years of age, but that pasture feeding conditions may affect quality significantly.

Establishment of reference or baseline conditions of chemical indicators in New Zealand streams and rivers relative to present conditions

The management of streams and rivers can be aided by knowledge of reference conditions. Data from >1000 sites across New Zealand was used to develop a technique to estimate median ammoniacal-N, clarity, Escherichia coli, filterable reactive phosphorus, nitrate-N, suspended solids, and total nitrogen and phosphorus values under reference conditions for streams and rivers as classified by the River Environment Classification (REC). The REC enabled us to account for natural variation in climate, topography and geology when estimating reference conditions. Values for minimally disturbed sites (i.e. <5% in intensive agriculture) were generally within the confidence limits for estimated reference values. Metrics that described: (1) the percentage of anthropogenic contribution to analyte values; and (2) the degree of enrichment beyond the reference conditions, showed that lowland sites classified as warm-wet, warm-dry or cool-dry exhibited the greatest anthropogenic input and enrichment. The consideration of natural variation by REC class informs the setting of water quality objectives through avoiding water quality limits or targets that are either too restrictive, and impossible to meet (e.g. below reference conditions), or too high, such that they have little ecological benefit. We recommend reference conditions be considered by regulatory authorities when assessing water quality impacts, objectives and limits.

Effects of plant-parasitic nematodes and rhizosphere microorganisms on the growth of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.)

A pot trial was carried out to study the effects of plant-parasitic nematodes and rhizosphere microorganisms on the growth of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). Plants were grown together in Horotiu sandy loam (Vitric Hapludand). The treatments consisted of: untreated field soil (UT); soil frozen to −20°C to reduce nematodes (FR); soil fumigated with chloroform to kill most soil organisms (FU); and fumigated soil inoculated with a layer of frozen soil to reintroduce organisms present in frozen soil (FUI). The mean wet weights of white clover and ryegrass grown in UT soil for 6–9 weeks were only 10 and 60%, respectively, of those grown in FR soil and 5.8 and 56%, respectively, of those grown in FU soil. The severe growth reduction of white clover in UT was attributed to early invasion of roots by two nematode species, Heterodera trifolii and Meloidogyne hapla, which were detected in stunted 7-day-old seedlings. In the FR and FUI treatments, the freeze-thaw process appeared to have killed the second stage juveniles but not the eggs, which hatched to release more juveniles to invade white clover roots. Plant growth in FR, and to a lesser extent in FUI treatments, was reduced in comparison with FU, where there was no nematode invasion. The bacterial numbers in surface-sterilized roots were unaffected by any of the treatments. This suggests that the entry of bacteria into root tissues is independent of the wounding caused by nematodes. The mean bacterial numbers of the medians (means of log cfus across treatments and plant species of the median numbers across replicates) for “total” bacteria, fluorescent pseudomonads, Gram-negative bacteria and Gram-positive bacteria from surface-sterilized roots were 4.26, < 2, 2.94 and 3.08 for the four treatments, respectively. The most common bacterial genera identified were Pseudomonas and Bacillus. Fungi isolated from surface-sterilized roots included Fusarium oxysporum, Codinaea fertilis and many sterile fungi, with F. oxysporum being the most common identified fungus in FU and FUI treatments. C. fertilis was killed by the soil freezing process. F. oxysporum did not appear to be associated with a decrease in dry matter production of either white clover or ryegrass, but C. fertilis may have adversely affected the ryegrass dry matter production in the treatment UT.

A field study of the behavioral and physiological effects of varying amounts of shade for lactating cows at pasture

Shade reduces the negative effects of heat load, but little is known about how much is required for efficient cooling in commercial settings. The effect of the amount of shade on 8 Holstein-Friesian herds was studied for 2 consecutive summers (mean temperature: 23 °C) on 6 commercial, pasture-based dairy farms. Farms varied in the amount of natural shade provided (range: 0 to 15.6m(2) shade/cow). Time spent in shade, near water, eating, ruminating, lying, and standing were recorded between 1000 and 1530 h in 31 shaded and 11 unshaded paddocks using 20-min instantaneous scan observations of 15 focal cows/herd. Respiration rate and panting score (0 to 4.5) was recorded for focal animals once per hour. The total numbers of cows in shade, near water, and with panting scores ≥ 2 were recorded every 30 min. Cows without shade spent 4% more time lying than cows with shade (standard error of the difference, SED = 1.9%). A larger proportion of the herd had panting scores ≥ 2 when no shade was available (6 vs. 2% of the herd, SED = 1.2%), and respiration rates were higher by 8 breaths/min in cows without shade (SED = 4.7 breaths/min). Under the conditions tested, the maximum proportion of the herd that was observed using the shade increased by 3.1% for every 1-m(2) increase in shade size [standard error (SE) = 1.51%], and all cows were first seen simultaneously using shade when 2m(2)/cow was provided. For every 1-m(2) increase in shade, 0.3% fewer cows had panting score ≥ 2 (SE = 0.12%). We observed no significant relationships between the amount of shade available and any other variables. Although additional work is required to make specific recommendations, these results indicate that providing more shade allowed a higher proportion of animals to use this resource and reduced respiratory signs of heat load.

Differences in the post‐mortem kinetics of the calpain system in meat from bulls and steers

Abstract Strip loins (longissimus thoracis et lumborum) from bulls with normal ultimate pH (NOR, pHu 5.7), and steers were compared after storage at 15°C. HI samples had higher shear forces 120 hours post‐slaughter than NOR and steer samples (P < 0.05). Calpastatin and μ‐calpain activities were higher in the NOR bulls than in steers, but the rates of decline in these activities were more rapid in NOR samples. The activity of μ‐calpain was low at all times and appeared to be involved in the increased toughness of the HI samples. The activity of m‐calpain and the calpastatin : μ‐calpain activity ratio provided a good prediction of shear force 120 hours post‐slaughter in the strip loin (R2 = 0.70; P < 0.001). This suggests that calpastatin, μ‐calpain, and m‐calpain all play a role in tenderisation and that on‐farm and pre‐slaughter management rather than post‐slaughter treatment need to be used to decrease the incidence of high pH meat.