Energy balance of individual cows can be estimated in real-time on farm using frequent liveweight measures even in the absence of body condition score

Existing methods for estimating individual dairy cow energy balance typically either need information on feed intake, that is, the traditional input–output method, or frequent measurements of BW and body condition score (BCS), that is, the body reserve changes method (EB_body). The EB_body method holds the advantage of not requiring measurements of feed intake, which are difficult to obtain in practice. The present study aimed first to investigate whether the EB_body method can be simplified by basing EB_body on BW measurements alone, that is, removing the need for BCS measurements, and second to adapt the EB_body method for real-time use, thus turning it into a true on-farm tool. Data came from 77 cows (primiparous or multiparous, Danish Holstein, Red or Jersey) that took part in an experiment subjecting them to a planned change in concentrate intake during milking. BW was measured automatically during each milking and real-time smoothed using asymmetric double-exponential weighting and corrected for the weight of milk produced, gutfill and the growing conceptus. BCS assessed visually with 2-week intervals was also smoothed. EB_body was calculated from BW changes only, and in conjunction with BCS changes. A comparison of the increase in empty body weight (EBW) estimated from EB_body with EBW measured over the first 240 days in milk (DIM) for the mature cows showed that EB_body was robust to changes in the BCS coefficients, allowing functions for standard body protein change relative to DIM to be developed for breeds and parities. These standard body protein change functions allow EB_body to be estimated from frequent BW measurements alone, that is, in the absence of BCS measurements. Differences in EB_body levels before and after changes in concentrate intake were calculated to test the real-time functionality of the EB_body method. Results showed that significant EB_body increases could be detected 10 days after a 0.2 kg/day increase in concentrate intake. In conclusion, a real-time method for deriving EB_body from frequent BW measures either alone or in conjunction with BCS measures has been developed. This extends the applicability of the EB_body method, because real-time measures can be used for decision support and early intervention.     

Energetic constraints on mating performance in the sand goby

I tested the effect of food addition on reproductive successin male sand gobies, Pomatoschistus minutus, by comparing food-supplementedmales with unfed, control males. The sand goby is a small marinefish with paternal egg care. The males were breeding in artificialnest sites in otherwise natural conditions in the field. I quantifiedenergy reserves by extracting nonpolar lipids. The food supplementimproved the fat reserves of the fed males as compared to unfedmales. Fed males spent more time at the nest, whereas unfedmales spent a much smaller proportion of their time at the nest.As a consequence, fed males mated sooner than unfed males andtended to get more eggs. In the unfed group, mating speed wascorrelated to body length so that bigger males mated sooner.The results suggest that the reproductive success of breedingsand goby males is constrained by the availability of energybut that this constraint is most severe for small males andless severe for bigger males. Energy availability through itseffect on condition will affect the investment in reproductiveeffort.     

Does thermal-related plasticity in size and fat reserves influence supercooling abilities and cold-tolerance in Aphidius colemani (Hymenoptera: Aphidiinae) mummies?

(1) The parasitoid Aphidius colemani was reared at 15 or 25 °C to induce variation in size and fat reserves; SCP and cold-tolerance were compared. Insects from both temperatures were also exposed to constant or fluctuating cold-exposure.

(2) The lower SCP in mummies reared at 25 °C may be partially explained by their smaller size, a negative relationship being observed between SCP and size.

(3) A bimodality was observed in SCP distributions, with two modes around −26 and −22 °C, likely because of presence/absence of gut content.

(4) The type of exposure had a striking impact, mortality being considerably lower under fluctuating regime.

(5) While energy storage is an important factor, vulnerability to chill-injury is supposed to be the primary factor regulating survival at low temperature.     

Interspecific variation in the resprouting responses of Acacia species following simulated herbivory in a semi‐arid southern African savannah

Plants have evolved a diverse suite of tolerance traits against herbivory, including compensatory growth, increased photosynthesis and activation of dormant meristems. We studied the responses of five Acacia species to simulated herbivory in a semi‐arid southern African savannah. We clipped terminal shoots of five juvenile Acacia species (Acacia rehmanniana, A. nilotica, A. karroo, A. arenaria and A. gerarrdii) to simulate herbivory. We then determined biomass change after 5 months and also counted the number of resprouts and measured their length and diameter. All clipped shoots produced resprouts, with all the Acacia species compensating for the lost biomass. We found considerable interspecific variation in the compensation for biomass lost to herbivory in the five Acacia species. Resprouts biomass ranged from two times in A. arenaria to four times that removed in A. karroo. Acacia karroo produced many resprouts, while A. arenaria produced very few resprouts (4 vs 15 resprouts). The relationship between the number of resprouts and their growth also varied among the different Acacia species. We conclude that the response of Acacias to herbivory ranges from prolific resprouters (such as A. karroo) to poor resprouters (e.g. A. arenaria).     

Dietary effects on growth, reproduction, body composition and stress resistance in the terrestrial isopods Oniscus asellus and Porcellio scaber

The effect of differences in food composition on growth, body composition and cold tolerance of the isopods Porcellio scaber (Latreille) and Oniscus asellus (L.) has been studied. The effect on reproduction of P. scaber was included. Total lipid and protein content remained the same in O. asellus, given food with a nitrogen content of 2.4, 2.5, 2.8 or 3.1% for 8 weeks. Those fed on 3.1% N gained significantly more weight than those fed on 2.4, 2.5 or 2.8% N. Cold tolerance after a period of low temperature acclimation could not be tested, due to high mortality at the subzero treatment. Haemolymph osmolality increased after the winter acclimation for all food treatments. Juvenile P. scaber, given food of 1.8, 2.5 or 3.1% N, showed no difference in growth over 18 weeks, nor in body composition over 14 weeks. Diet did not influence cold tolerance ability and haemolymph osmolality remained the same with changing cold tolerance of the animals. Gravid females of P. scaber were separated to examine the effect of diet on reproduction. Diet did not influence the number of juveniles, nor their weight. In all food treatments, a significant correlation was found between the weight of the female and the number and weight of her offspring.     

Effects of Water Deficit during Germination of Wheat Seeds

Germinating seeds of spring wheat (Triticum aestivum L.) were tolerant to dehydration up to the 4^th day following imbibition and from the 5^th day the seedling survival decreased. Dehydration also inhibited the rate of seed dry mass depletion and seedling dry matter accumulation and increased the content of soluble sugars both in grain and seedlings. Glucose supplied either to dry seeds or to 4-d-old seedlings increased survival of dehydrated seedlings. In contrast, exogenously supplied non-readily metabolizable sorbose and mannose suppressed seedling survival.     

Rapid community change at a tropical upwelling site in the Galápagos Marine Reserve

The high biodiversity of tropical marine communities has attractedconsiderable interest, yet we still lack a clear understanding of the tempo ofdiversity change in these systems []. Knowledge of the conditions associated with fast or slow community assembly inthe tropics would enhance our ability to predict recovery from natural andanthropogenic disturbance and to conserve biodiversity. Here we report anunusually rapid doubling of species richness within a year in a tropical,subtidal sessile invertebrate community in a protected (non-extractive) zone ofthe Galápagos Marine Reserve (GMR). Diversity changes in the rock wallcommunity were accompanied by large increases in the percent cover, densityand/or biomass of sponges, barnacles, ascidians, and an ahermatypic coral,Tubastrea coccinea, over the 1-year studyperiod (1999–2000). Barnacle (Megabalanuspeninsularis) and ascidian (Didemnum cineraceum)biomasses increased by an order of magnitude from 1999 to 2000. The greaterabundance of sessile invertebrate prey was accompanied by significant increasesin the abundance of barnacle and Tubastrea predators(Hexaplex princeps, Asperiscalabilleeana). An estimated 37% of barnacle tissue biomass productionwas consumed in 1 year. Temperature monitoring during the studyperiod showed that this site is characterized by strong upwelling, where rapid,3.0–9.0 °C decreases in temperature occurred at harmonicsof the semi-diurnal tidal periodicity during warm (January–February), butnot during cool months (June–July). Short-term acoustic current metermeasurements revealed strong, highly variable upwelling at the study site, withevents ranging from 2–111 min in duration and maximumupwelling velocities of 32.3 cm s^–1. Thesefindings suggest that the turnover of diversity and biomass may be unusuallyrapid at tropical upwelling sites, especially where invertebrate predators areprotected from harvesting. Consequently, upwelling sites may warrant specialconsideration in the planning of marine reserves to ensure the conservation ofbiodiversity.