Corn supplementation as a winter-feeding strategy alters maternal feeding behavior and endocrine profiles in mid- to late-gestating beef cows1

This study evaluated the effects of early (EW) and late (LW) weaning on calf post-weaning growth performance and carcass characteristics. It also quantified the effects of EW and LW in combination with three winter feeding strategies on cow growth, reproductive performance and cost of production. EW calves were weaned in late August, while LW calves were weaned 56 d later in late October. The three cow winter feeding strategies were: (1) traditional (TD), or straw fed ad libitum and barley (Hordeum vulgare L.) silage fed every day; (2) alternate day (AD), or straw fed ad libitum and equivalent amounts of barley silage fed every second day (AD); and (3) swath graze (SG), or swath grazing whole-plant barley, cut in the soft dough stage. The study was conducted over three production cycles (1997/1998, 1998/1999 and 1999/2000). EW calves weighing 213 kg and fed a backgrounding diet (82% barley silage: 18% concentrate) for 56 d, grew 0.36 kg d-1 (EW = 0.61 ± 0.02 kg d-1; LW = 0.97 ± 0.02 kg d-1; P < 0.001) slower from early to late weaning than LW calves (210 kg) on pasture nursing their mothers. Over the next 124–128 d, EW and LW calves fed the backgrounding diet grew similarly at 0.95 ± 0.01 and 0.93 ± 0.02 kg d-1, respectively. Both groups of calves also grew similarly during the finishing phase (EW = 1.56 ± 0.04 kg d-1; LW = 1.53 ± 0.05 kg d-1; P = 0.62), such that at slaughter, EW and LW calves were the same age (461 ± 4 vs. 455 ± 5 d, P = 0.326) and weight (522 ± 5 vs. 515 ± 6 kg, P = 0.390), with similar levels of carcass backfat, yield and quality grade. EW cows weighed 12 to 15 kg more (P < 0.01) in mid-November (first winter feeding), mid-February (pre-calving) and late-May (prebreeding) and tended to have a shorter calving span (49 vs. 62 d, P = 0.07) than the LW cows. Calving interval, calving pattern and cumulative open and cull rates, monitored over three consecutive production cycles, were similar for EW and LW cows. Differences (P < 0.05) in body weight were observed between winter feeding treatments. SG cows had the lowest weight (605 kg) and backfat thickness (4.5 mm) at pre-breeding; AD cows were intermediate (623 kg and 5.1 mm); and TD cows were heaviest (639 kg) with the most backfat (6.4 mm). Calving interval, length of the calving span, calving pattern and cumulative open and cull rates were similar among the winter feeding strategies for cows monitored over three production cycles. Swath grazing required 38.4% less labour than traditional feeding and 20.9% less labour than alternate day winter feeding. Total cash cost over the first 100 d of winter feeding for the SG winter feeding strategy was $70.00 cow-1 less than TD (45.5%) and $56.70 cow-1 less than AD (40.4%) winter feeding strategies. On average, 300 and 314 cow swath grazing d ha-1 were required to cover the cost of feed in the TD and AD winter feeding strategies, respectively. Key words: Beef cows, Western Canadian Parkland, swath grazing, alternate day, early and late weaning

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Hippocampal Circuits for the Hunger-Dependent Control of Feeding Behaviour

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.1100 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A540-A540

Author(s):

Ryan Wei Shien Wee ◽

Andrew MacAskill

Keyword(s):

Feeding Behavior ◽

Food Consumption ◽

Calcium Imaging ◽

Feeding Strategy ◽

Ghrelin Receptor ◽

Internal States ◽

Decision Making Processes ◽

Free Feeding ◽

Motivated Behaviors

Abstract Background: Feeding behavior is a complex motivated behavior that requires organisms to integrate features of the environment, such as food availability and value, and internal states, such as hunger, in deliberating over the decision to eat. The hippocampus - a brain region classically thought to support spatial cognition and episodic memory - is increasingly recognised to contribute to such decision-making processes. This function makes the hippocampus a likely candidate in supporting the higher-order decisions that underpin motivated behaviors such as feeding. However, the role of the hippocampus during free-feeding behavior has not been examined. Methods and Results: To address this question, we used in vivo calcium imaging during feeding behavior in mice to monitor the neural activity of the ventral subiculum (vS) - one of the main output structures of the ventral hippocampus. In a free-feeding task, we found that the vS encoded the investigative approach phase of feeding behavior and that activity during this period correlated with the probability of transitioning from food investigation to consumption. Calcium imaging during an operant task confirmed the specific encoding of preparatory behaviour preceding food consumption. Furthermore, the sensitivity of vS to the hunger state could be mapped to vS neurons projecting to the nucleus accumbens (vS-NAc). Ghrelin - a hormone signalling the hunger state - altered synaptic transmission specifically in vS-NAc neurons, and molecular knockdown of the ghrelin receptor was required for the hunger sensitivity of vS-NAc. Consequently, both reducing ghrelin signalling in vS-NAc neurons through molecular knockdown and artificially elevating vS-NAc activity through optogenetics were sufficient to shift the feeding strategy of animals, effectively curtailing overall food consumption. Conclusion: In summary, these results provide evidence for a hippocampal circuit that integrates hunger state signals to regulate the decision to eat.

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Selective Feeding by a Predatory Sea Star Across a Depth Gradient in Northern Patagonia, Chile

Frontiers in Marine Science ◽

10.3389/fmars.2021.636208 ◽

2021 ◽

Vol 8 ◽

Author(s):

Ignacio Garrido ◽

Luis Miguel Pardo ◽

Ladd E. Johnson ◽

Dirk Schories

Keyword(s):

Feeding Behavior ◽

Prey Selection ◽

Feeding Strategy ◽

Benthic Communities ◽

Generalist Predator ◽

Subtidal Zone ◽

Polar Regions ◽

Depth Gradient ◽

Sea Star ◽

Sea Stars

Sea stars often function as keystone predators in food webs of intertidal and subtidal communities, especially in temperate and sub-polar regions. In South America the sea star Cosmasterias lurida is distributed along both the Atlantic and Pacific coasts of Patagonia and is one of the most conspicuous and abundant benthic predators in the shallow subtidal zone (<25 m). Its feeding strategy and prey selection are, however, still poorly known. This study describes the feeding behavior of C. lurida at a site in the Seno del Reloncaví (Chile), assessing its abundance, size and prey selection in the field relative to observed prey abundance and size along a bathymetric gradient. We hypothesized that C. lurida is a generalist predator, feeding on suitable prey according to their availability. However, we found that this predator only consumed a limited number (7 of 48) of potential prey species, primarily the slipper limpets Crepipatella spp. and the mussels Aulacomya ater and Mytilus chilensis. Electivity analysis revealed a clear preference for one mussel (A. ater) but not the other (M. chilensis) as well as depth-dependent selectivity for the slipper limpets, which changed from avoidance to preference with increasing depth. Sea star densities varied with depth, peaking between depths of 5 and 10 m, but the size of sea stars and the size of their prey did not vary significantly along a depth gradient. No significant correlations were found with the most commonly selected prey. These results would indicate that while this predator may be a generalist–opportunist, its feeding behavior is context-dependent and its high selectivity for certain species suggests that this sea star plays a key role structuring subtidal benthic communities in Patagonia.

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Mandibular force profiles and tooth morphology in growth series of Albertosaurus sarcophagus and Gorgosaurus libratus (Tyrannosauridae: Albertosaurinae) provide evidence for an ontogenetic dietary shift in tyrannosaurids

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2020-0177 ◽

2021 ◽

Author(s):

François Therrien ◽

Darla K. Zelenitsky ◽

Jared T Voris ◽

Kohei Tanaka

Keyword(s):

Feeding Behavior ◽

Feeding Strategy ◽

Large Body ◽

Biomechanical Properties ◽

Bite Force ◽

Growth Stages ◽

Tooth Morphology ◽

Growth Series ◽

Dietary Shift ◽

Force Profiles

The albertosaurines Albertosaurus sarcophagus and Gorgosaurus libratus are among the best represented tyrannosaurids, known from nearly complete growth series. These specimens provide an opportunity to study mandibular biomechanical properties and tooth morphology in order to infer changes in feeding behavior and bite force through ontogeny in tyrannosaurids. Mandibular force profiles reveal that the symphyseal region of albertosaurines is consistently stronger in bending than the middentary region, indicating that the anterior extremity of the jaws played an important role in prey capture and handling through ontogeny. The symphyseal region was better adapted to withstand torsional stresses than in most non-avian theropods, but not to the extent seen in Tyrannosaurus rex, suggesting that albertosaurine feeding behavior may have involved less bone crushing or perhaps relatively smaller prey than in T. rex. The constancy of these biomechanical properties at all known growth stages indicates that although albertosaurines maintained a similar feeding strategy through ontogeny, prey size/type had to change between juvenile and mature individuals. This ontogenetic dietary shift likely happened when individuals reached a mandibular length of ~58 cm, a size at which teeth shift from ziphodont to incrassate in shape and bite force begins to increase exponentially. The fact that large albertosaurines were capable of generating bite forces equivalent to similar-sized tyrannosaurines suggests that no significant differences in jaw closing musculature existed between the two clades and that the powerful bite of T. rex is the result of its large body size rather than of unique adaptations related to a specialized ecology.

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